The juridicial statute of Olivenza
The official position of the Portuguese Government
Where is Olivenza?
The size of Olivenza
Brief history of Olivenza
Grounds for the portuguese rights
Brief Bibliography of Olivenza



The juridicial statute of Olivenza
Olivenza is a Portuguese territory illegaly occupied by Spain.
Portugal does not recognize the Spanish sovereignty over the Olivenza territory. Therefore, the border between these two countries in the Olivenza region has never been defined– in the delimitation of the border between the two Iberian states 100 landmarks have not yet been placed.
The rigths of sovereignty that Portugal possesses over Olivenza are unarguable and no expert in International Law can question it.
The Portuguese Constitution, in Article 5, number 3, makes it impossible for that territory to be given to Spain. Thus the only solution to this peninsular litigation lies in the fulfilment of the Vienna Treaty of 1815, whereby Spain pledged to return Olivenza to Portugal, which has not happened so far.


The official position of the Portuguese Government
Although statements made by those responsible for the Portuguese diplomacy are rare, the principle that Portugal does not recognize Spanish sovereignty over the Olivenza territory is unambiguous. In the past seven years only three public testimonies by the Portuguese diplomacy are known concerning the title to Olivenza, but these testimonies are clear enough to understand the official position of the Portuguese Ministry of Foreign Affairs.

In 1988 the Portuguese ambassador Carlos Empis Wemans, Portugal’s representative in the International Comission of Portuguese-Spanish Limits, stated in the Portuguese newspaper "Diário de Lisboa":
«Portugal has never officially recognized the situation. From a legal point of view, Olivenza is still ours. So, when answering occasional contacts from Spain about problems in the region, we always say that  Olivenza is Portuguese de jure».
More recently, this position was reasserted when the project of reconstruction of the Olivenza Bridge was under discussion. The Olivenza Bridge was built by the Portuguese King Manuel I (1495-1521) and was destroyed in 1709 during the War of Succession. This bridge has remained impassable until today, making it difficult to travel between Elvas and Olivenza over the Guadiana River, which is nowadays the de facto border, but not the juridically acceptable border between Spain and Portugal.
In the Iberian Summit in 1990, the Portuguese Prime Minister Cavaco Silva reached an agreement about the reconstruction of the Olivenza Bridge as a cross-border enterprise, as previously negotiated by the Portuguese and Spanish Secretaries of State for Regional Planning, Isabel Mota and Jose Borrell respectively.
Four years later, in the beginning of March, the Portuguese Ministry of Foreign Affairs, presided by Durão Barroso, blocked the agreement, thus preventing the project from being carried out. Ambassador Pinto Soares, the Portuguese representative in the International Commission of Limits, refused to discuss the file on the bridge, stating that «the Portuguese State cannot get involved in any project that involves the recognition of the borderlines in a place on which there is no consensus». «To participate in such an enterprise», expained a person from the Ministry of Foreign Affairs to the Portuguese newspaper "Público", «would mean that Portugal recognizes Spanish sovereignty over Olivenza».

The astute way in which Spain wanted to achieve recognition of its illegal occupation of Olivenza turned into a clear affirmation of Portugal’s rights to the territory. As the Portuguese administration considers that the Olivenza territory is part of its space of sovereignty, the Portuguese Ministry of Foreign Affairs imposed the building of the bridge as an exclusively Portuguese enterprise, rather than a joint, cross-border enterprise. The peninsular states like to deal with the Question of Olivenza in a silent way; that is why the final agreement was negotiated in the Iberian Summit of November 1994, with no great echoes of the dissension and susceptibilities involved reaching the mass media
The most recent official assertion that Olivenza is part of the Portuguese territory occurred in 1995 in the context of the project of the Alqueva Dam, which will submerge about 2,400 hectares of land in the Spanish municipalities of Badajoz, Cheles, Alconchel and Villanueva del Fresno, plus approximately 1,000 hectares in Olivenza.
In the negotiations about this subject conducted by the two peninsular states, the Portuguese authorities, including the Ministry of the Environment and the Ministry of Foreign Affairs, sent to Madrid, in March 1995, a detailed study of the consequences that the project will have on Spanish territory. As Portugal does not recognize Spanish sovereignty over Olivenza, information on this legally Portuguese territory was not included in the 13 volumes of the study sent to the Spanish authorities. Only one week later, in deference to the Spaniards and to simplify technical aspects, did our administration send information in which data on Olivenza was included. But, in order to emphasise the Portuguese position, the study was entitled ‘Territory of Spain and Olivenza’, which clearly demonstrates that the Portuguese administration does not consider Olivenza as part of Spain.


Where is Olivenza?
Olivenza is situated in the Alto Alentejo (a province in the south of Portugal), on the left bank of the River Guadiana, almost in front of Elvas city, about 24 Km south of Badajoz. The territory of Olivenza has got a triangular configuration, with two of its vertices lying in the River Guadiana and the third one going south-east into Spain.
If Olivenza went over to Portuguese administration, it would probably become part of the District of Portalegre


The size of Olivenza
In the world there are 21 independent countries smaller than Olivenza, and about 20 non-autonomous territories awaiting their self-determination also have a smaller area than Olivenza.

Besides the town, the territory of Olivenza includes seven villages:
S. Francisco,
S. Rafael,
Vila Real,
S. Domingos de Gusmão,
S. Bento da Contenda,
S. Jorge de Alor e
Táliga.

In all, Olivenza is 750 Km2 in area. Its area is slightly superior to that of countries like Singapore or Bahrain.

To have a clearer idea, the most important Portuguese municipalities (Lisbon and Oporto) put together cover an area six times smaller than Olivenza.
Gibraltar is less than 6 Km2 in area; it is 125 times smaller than Olivenza. If the Spanish Government claims the restitution of Gibraltar from the United Kingdom, on historical grounds but with no juridical arguments, why cannot Portugal demand that Spain give back Olivenza, since there are no doubts about the Portuguese rights to this territory?

Population of Olivenza Territory*

Olivença 8.274 Inhab.
S. Francisco de Olivença 468 Inhab.
S. Rafael de Olivença 265 Inhab.
Vila Real 96 Inhab.
S. Domingos de Gusmão 31 Inhab.
S. Bento da Contenda 564 Inhab.
S. Jorge de Alor 478 Inhab.
Táliga 736 Inhab.

TOTAL 10.912 Inhab. (* Census of 1991)

Just like the other villages in the Alentejo, a province in the South of Portugal, the territory of Olivenza is deeply depopulated.
Most of its inhabitants concentrate in Olivenza.
The inhabitants of the town are mainly Spanish colonists brought there to populate the Portuguese fortress.
It is in the rural area of Olivenza that the Portuguese culture still survives, in spite of the Spanish colonialist, and often repressive, strategies.


Brief history of Olivenza

1297 - Through the Alcanizes Treaty between Dinis, King of Portugal and Fernando IV, King of Castela, Olivenza was definitely made part of the Portuguese territory.
1298 - Dinis, King of Portugal, granted "Carta de Foral" (municipal constitution) to Olivenza and built new walls. 

1488 - João II, King of Portugal, built the tower of Olivenza (Torre de Menagem). 

1510 - Manuel I, King of Portugal, granted new “Foral” (municipal constitution) to Olivenza. 
This King built new fortifications and the Olivenza Bridge, which linked Olivenza to Elvas (now a Portuguese town). Later, this bridge became known as Nossa Senhora da Ajuda Bridge. 
In the reign of King Manuel I the construction of Madalena's Church started. This church would be the residence of the Bishop of Ceuta for many years.

1580 - Dynastic Union between Portugal and Spain.

1640, December 1st - Restoration of the Portuguese Independence. 

1668 - Peace treaty between Spain and Portugal, thus ending the Restoration Wars. 
Portugal kept the borders defined by the Alcanizes Treaty (1297). 
Spain never questioned the Portuguese sovereignty in Olivenza, despite the constant fights in the bordering zone.

1709 - In the aftermath of the Spanish Succession War, the Olivenza Bridge was destroyed by Spanish forces and has remained so until today.

1801, January 29th - Spain and France signed an invasion treaty against Portugal to make it abandon the Portuguese-British Alliance and close its ports to British ships. 

1801, February 27th - Spain declares war on Portugal. 

1801, May 20th - The Spanish troops invade the South of Portugal and occupy Olivenza, Juromenha and, a few days later, Campo Maior. 

1801, June 6th - Peace Treaty of Badajoz between Portugal on one side, and on the other side Spain and France. 
In this treaty, signed because of the threat of invasion of Portugal by the French troops stationed in Ciudad Rodrigo, the following was agreed upon:
Portugal would give Olivenza to Spain; 
Portugal would close its ports to British ships; 
Portugal would pay France an indemnification of 15 million pounds ("libras tornesas") ; and 
would accept the Guiana borders as far as the mouth of the River Arawani.
The Treaty of Badajoz stipulated that the breach of any of its articles would lead to its cancellation, which came to pass in 1807. 

1807, October 27th - The Treaty of Fontainbleau, signed between Spain and France, defined the occupation of Portugal and its division into three parts: the Province of Entre Douro-e-Minho for the King of the Etrúria; the Principality of the Algarves for Spanish minister D. Manuel Godoy; the remaining provinces and overseas territories would be distributed by a future agreement.

1807, November - the Spanish and French forces started the occupation of Portugal, forcing the Portuguese Royal Family to transfer the government to Brazil. 
By signing the Treaty of Fontainbleau and invading Portugal, Spain brought about the cancellation of the Treaty of Peace of Badajoz, losing the rights that it could have acquired in Olivenza. 

1808, May 1st - the Prince Regent of Portugal D. João published, in Rio De Janeiro, a manifesto in which the Treaty of Badajoz, annulled by the 1807 invasion, was repudiated.

1809, July - Portugal, through D. Pedro de Sousa e Holstein, future Duke of Palmela, presented to the "Junta Central", in Seville, an official order of  restitution of the Territory of Olivenza. 

1810, February 19th - Treaty of alliance and friendship between Portugal and Britain, whereby Great-Britain pledged to help Portugal to regain possession of Olivenza, receiving in return the exploration of the Portuguese establishments of Bissau and Cacheu for a period of 50 years. 

1810 - Portugal negotiated a treaty with the Regency Counsel of Spain, whereby Olivenza should be given back to Portugal.

1811, April 15th - Portuguese military forces occupy Olivenza. 
Beresford, British marshal who occupied the rank of Head-general of the Portuguese army, ordered the restitution of Olivenza to the Spanish authorities, probably so that Great-Britain would not lose the advantages gained with the 1810 Treaty between Portugal and Britain. 

1814, May 30th - The Treaty of Paris, in article 3 of the Amendments section, declared the 1810 treaties of Badajoz and Madrid null and void. 

1815, June 9th - According to the Final Minutes of the Congress of Vienna, in article 105, the Portuguese rights to the Territory of Olivenza were recognized. 

1815, October,  27 - Expecting the quick restitution of Olivenza, Prince Regent João VI nominated D. Jose Luiz de Sousa as Plenipotentiary. He should proceed to the acceptance of the territory.

1817, May 7th - Spain signed the Treaty of Vienna, «recognizing the justice of the claims formulated by His Highness, the Prince Regent of Portugal and Brazil, on the village of Olivenza and the other territories yielded to Spain by the Treaty of Badajoz of 1801»; and committing to make «the more efficient efforts so that the restitution of the above-mentioned territories to Portugal wil take place», which should «happen as soon as possible». 

1818 - To decide a territorial litigation between Portugal and Spain in South America, a proposal of a treaty was drafted, whereby Spain accepted the restitution of Olivenza. 

1840 - The Portuguese language was forbidden in the Territory of Olivenza, including in churches. 

1858 - Isabel II of Spain granted the title of Town to Olivenza. 

1864, September 29th - a covenant between Portugal and Spain was signed, demarcating the border from the estuary of the River Minho to the confluence of the River Caia with the River Guadiana. The definition of the territorial limits was not pursued because of the Question of Olivenza. 

1903 - D. Carlos, King of Portugal, requested the Spanish monarch that justice be made in the Litigation of Olivenza. 

1911 - The Portuguese Senator Ramos da Costa raised the question of Olivenza in the Senate. 

1918/19 - With the end of the First World War, the Portuguese Government studied the possibility of taking the Question of Olivenza to the Peace Conference. With this purpose, the Ambassador Teixeira de Sampaio wrote an extensive report. 
As Spain did not participate in the world-wide conflict, the intervention of the international community in the Litigation of Olivenza was not possible.

1926, June 29th - Portugal and Spain celebrated an agreement for the demarcation of the border from the estuary of the River Cuncos to the estuary of the River Guadiana.
Owing to the Problem of Olivenza, the border between Portugal and Spain from the estuary of the River Caia to the estuary of the River Cuncos has not been demarcated until today.

1936-39 - Spanish Civil War. During the Spanish conflict, Colonel Rodrigo Pereira Botelho offered to occupy Olivenza. The Portuguese Regiment 8, stationed in Elvas, was prepared to take Olivenza but was hindered by hierarchic superiors. A group of Portuguese legionaries had the same intention. Some ‘oliventinos’ (i.e. inhabitants of Olivenza) who defended Olivenza’s reintegration into Portugal, will have been eliminated during the turmoil the Civil War. The ‘oliventinos’ who took refuge on the Portuguese side of the Guadiana were sheltered, while the Spaniards were sent back to their territory.

1938, August 15th - The Pro-Olivenza Society (Sociedade Pró-Olivenza) was established.

1944/45 - In Lisbon, the Group of the Friends of Olivenza (Grupo dos Amigos de Olivenza) was formed.

1952 - In the International Commission of Limits, Portugal claimed ownership of the Territory of Olivenza. 

1958 - Humberto Delgado was elected as President of the General Assembly of the Group of the Friends of Olivenza. 

1958-59 - Portugal reaffirmed its rights to Olivenza in the International Commission of Limits. 

1965, February 13th - General Humberto Delgado was assassinated by the Ribeira de Olivenza. It is thought that his body passed in Olivenza on the way to Villanueva del Fresno, where it was abandoned. 

1968 - A covenant between Portugal and Spain was signed, guaranteeing the Portuguese ownership of the two banks of the Guadiana, since the confluence of the Caia to Mourão. Portugal kept its claims to the Territory of Olivenza. 

1974 - A Spanish legal consultant of the International Commission of Limits recognized Portugal’s right to claim ownership of Olivenza. 

1981 - Admiral Pinheiro de Azevedo assumed leadership of the Group of the Friends of Olivenza. 
This former Prime-Minister of Portugal conceived a plan to occupy Olivenza in a pacific way, which did not materialize due to lack of cooperation of the organs of government and to the indifference of the Portuguese public opinion. To make his project known, Pinheiro de Azevedo published a book on the subject of Olivenza and visited this town. His trip to Olivenza generated great tension, therefore Spain sent an enormous contigent of the Civil Guard to prevent problems. 

1988 - The Portuguese Ambassador Carlos Empis Wemans, Portugal’s representative in the International Commission of Limits, stated to the Diário de Lisboa, a Portuguese daily newspaper: 
«Portugal has never officially recognized the situation. From a legal point of view, Olivenza is still ours. So, when answering occasional contacts from Spain about problems in the region, we always say that  Olivenza is Portuguese "de jure"».

1990 - In the Iberian Summit, the prime-ministers of Portugal and Spain signed a covenant for the reconstruction of the Olivenza Bridge, a joint project, which put the Portuguese rights to Olivenza at risk since it could be understood as a recognition of the border in the Guadiana. 

1990, August - the Committee Portuguese Olivenza was legally constituted. 

1992 - The television programme ‘Contradictions’ (on RTP - Channel 2, one of the Portuguese state broadcasting stations) showed a debate on the Question of Olivenza, in which the former Minister of Foreign Affairs, Ambassador Franco Nogueira, participated. 

1994, March - The Portuguese Ministry of Foreign Affairs, headed by Durão Barroso, blocked the execution of the project of reconstruction of the Olivenza bridge. The Portuguese Ambassador Pinto Soares, the Portuguese representative in the International Commission of Limits, refused to discuss the file on the bridge, stating that «the Portuguese State cannot be involved in any project that involves the recognition of the borderlines in a place on which there is no consensus.».

1994, November - In the Iberian Summit of Oporto, an agreement was reached that the bridge be reconstructed by Portugal, without Spanish intervention, so that the Portuguese rights to the Territory of Olivenza would not be put at stake.

1995, March - the Portuguese Ministry of Foreign Affairs and the Environment Ministry sent to Madrid a detailed study of the effects that the construction of the Alqueva Dam in Portugal would have on Spanish territory.
As Portugal did not recognize Spanish sovereignty on Olivenza, information on this legally Portuguese territory was not included in the 13 volumes of the study sent to the Spanish authorities. Only one week later, in deference to the Spaniards and to simplify technical aspects, did our administration send information in which data on Olivenza was included. But, in order to emphasise the Portuguese position, the study was entitled ‘Territory of Spain and Olivenza’, which clearly demonstrated that the Portuguese administration did not consider Olivenza as part of Spains.

1995, May - The Law School of the University of Lisbon organized a debate on the Question of Olivenza. The Spanish representatives did not attend the debate.


Grounds for the portuguese rights

Inexistence of border
In the delimitation of the border between Portugal and Spain 100 landmarks have not yet been placed, from no. 801 to no. 900. 
The two agreements of border definitions in 1864 and 1926 did not delimit a part of the Alentejo coincident with the Territory of Olivenza, as Portugal did not recognize Spanish sovereignty on the region and Spain continued to postpone the restitution of this Portuguese parcel of land. 

The Project of the Centre of Studies of Cross-border Architectures, created in Olivenza in 1995, contains the following elucidatory statement: 

«Desde una perspectiva diplomática, Olivenza resulta ser una materia pendiente entre ambos países, hasta el punto que la comisión interministerial encarregada de revisar los límites fronterizos entre ambos países, dejan permanentemente sobre la mesa la delimitación de los marcos fronterizos que se correspondem con el término minicipal oliventino.»

So that the Portuguese silence would not be taken as tacit recognition of the Spanish occupation, the Portuguese diplomacy has periodically reminded Spain of its rights to recover Olivenza.

Nullity of the Treaty of Badajoz
France and Spain had been planning to invade Portugal and to divide it between the two countries since the end of the Rossilhão campaign (1793-95). The result of the agreements celebrated between these two countries was the invasion of Portugal by Spanish troops, assisted by French forces. After the assault on the Alentejo on May 20th, 1801, the governor of Olivenza surrendered to the occupying army, without resistance. The governor of Juromenha also surrendered. 
Diplomatically weak and under threat of attack, the Portuguese government had to yield to the demands of Napoleon Bonaparte and Carlos IV, King of Spain. The Portuguese government signed the double Treaty of Badajoz of June 6th and of Madrid of September 29th, 1801.

Besides submitting to the vexatious French claims, Portugal had to recognize the Spanish ownership of «Olivenza, its territory and peoples from the River Guadiana onwards». This river was now the border between the two countries in that region. 
If Spain possessed some valid argument to justify its occupation of the Territory of Olivenza, it would base it on the Treaty of Badajoz of 1801. However, this treaty, as well as the Treaty of Madrid of the same year, lost its legal value; it is considered null and void.
The Treaty of Badajoz was negotiated between the two parties in conflict: Portugal, as the invaded state; France and Spain, as the invaders.
Putting an end to the negotiations, a double treaty of peace was drafted that would alternately be signed between Portugal and Spain and Portugal and France, both being valid as only one treaty, as diplomatically connected texts. Such is stated in the Preamble of the Treaty:

«Having the Plenipotentiaries of the three belligerent Powers reached an agreement, they decided to form two Treaties, though they are no more than one in their essential part, since the guarantee is reciprocal and none of them will be valid if there is any infraction of any of their Articles.»

Article 4 strengthens the principle of the unicity of the Treaties of Badajoz and is the ground for the Portuguese claims on their nullity. In this article, the following is stipulated: 

«If there is any infraction in this or another Article, the Treaty that is now established between the three Powers will be considered null, according to the principle of mutual guarantee, as expressed in the Articles of this Treaty.»

The reciprocity of validity or invalidity of the two treaties is clearly expressed in Article 8 of the French text, when it is stated that ‘toute infraction à ce Traité será regardée pair le Premier Consul comme une infraction au Traité actuel’, which means that any infraction of the Treaty between Portugal and France would constitute an infraction of the treaty between Portugal and Spain, since both constituted only one treaty.

There are several reasons for the nullity of the Treaty of Badajoz. Besides the fact that France did not meet the deadline for its ratification, as stipulated in Article 9, which led to the signature of the Treaty of Madrid on September 29th, 1801, the causes of the nullity of the Treaty of Badajoz are the following: 

1) Lack of manifestation of the free will of Portugal
The circumstances in which Portugal signed the Treaty of Badajoz, with the French and Spanish armies threatening to intensify violent action against the Portuguese territory, which they had partially occupied, violate the principle whereby any legal business is only valid if all parties manifest their free will. 
Portugal signed the Treaty of Badajoz not in the exercise of its full freedom, but coerced into doing it under threat of force. 

2) Treaty of Fontainbleau and the violation of Peace
The Treaty of Badajoz of 1801 was a ‘Peace Treaty,’ which is clearly expressed in its preamble. Article 1 stipulated that: 

«There will be peace, friendship and good correspondence between His Highness the Prince Regent of Portugal and the Algarves, and His Catholic Majesty El Rei of Hespanha, in the sea as on land, in all the extension of their Kingdoms and Dominions.»

In spite of having been attacked and invaded by the Spanish-French forces, for no other reason than the decision to refuse to abandon its alliance with Great-Britain, Portugal had to accept the Peace in dishonourable and humiliating circumstances. 
In exchange for the acceptance of the Peace, which took place under threat of bigger retaliation, Portugal assented to the demands of Spain and France, including the recognition of Spanish ownership of Olivenza. 

As stipulated in Article 4, the violation of the Peace implied the nullity of the Treaty of Badajoz. 
This would happen in 1807, when Spain and France signed the Treaty of Fontainbleau, which determined the division of Portugal into three parts. The two countries occupied Portugal few months later in order to accomplish this project. 
If Spain could claim any right to ownership of the Territory of Olivenza, it lost it irrevocably, when it annulled, on its responsibility, the only document of legal value on which it could base its sovereignty on that small parcel of land in the Alentejo.

3) Treaty of Paris of 1814
As a result of the invasion of Portugal by French and Spanish forces, which led the Royal Family to transfer the headquarters of the Portuguese Monarchy to Brazil, D. João, the Prince Regent of Portugal, had a Manifesto published, dated May 1st, 1808, which considered the Treaties of Badajoz and Madrid of 1801 ‘null and void’.  
On March 31st, 1814 the allied forces entered Paris, compelling Napoleon to abdicate. The hostilities that resulted from the Napoleonic Wars were suspended by a convention signed on April 23rd. D. João, Prince of Portugal, adhered to it on May 8th of the same year. 
On May 30th the Treaty of Paris was signed, which annulled the Treaty of Badajoz and Madrid of 1801. 
Additional Article no.3 determined: 

«Although the treaties, conventions and acts concluded between the two powers before the war are in fact annulled due to the state of war, the contracting parts have deemed it convenient to declare again that the aforesaid treaties of Badajoz and Madrid in 1801, and the convention signed in Lisbon in 1804, are null and void for Portugal and France, and that the two crowns mutually renounce all rights and deny any obligation that could result from them.»

Although the Treaty of Paris only directly annuls the above-mentioned treaties as far as France is concerned, the same applies to Spain, since the two treaties of Badajoz constitute only one, as they indelibly expressed. 
From this Additional Article one can also infer the legal doctrine according to which the state of war that followed the Treaty of Fontainbleau, annulled, by itself, the Treaties of Badajoz and Madrid of 1801. This confirms the inexistence of any ground that guarantees Spanish dominion over Olivenza. 

Determination of the Congress of Vienna
After Napoleon was defeated, in April of the year 1814, the European powers tried to reestablish, as far as possible, the order and borders in force in 1792. 
If the Treaty of Paris of May 30th of 1814 was the beginning of the peace process, the Congress of Vienna, which started on September 27th of the same year, was an attempt to resolve the many problems that were pending. 
Among the questions of greater interest to Portugal there was the problem of the border of the French Guyana and the restitution of Olivenza.

Spain tried to dissuade the Portuguese diplomacy from presenting the Question of Olivenza to the Congress of Vienna, with not very consistent promises of restitution of the territory. Suspecting the Spanish intentions, Portugal opted to try to decide the problem involving the several countries present in Vienna. 
Trusting that Olivenza might be restituted, the Portuguese diplomacy attempted to cancel the treaty of alliance between Portugal and England of 1810, whereby Portugal gave Bissau and Cacheu to Great-Britain, for a period of 50 years, in exchange for British support to the restitution of Olivenza. 

Besides accomplishing this, the Portuguese representatives in the Congress of Vienna - D. Pedro de Sousa Holstein, D. António Saldanha da Gama and D. Joaquim Lobo da Silveira - succeeded in having the Portuguese right to the re-incorporation of Olivenza decreed. Article 105 of the treaty defined: 

«Recognizing the justice of the claims formulated by His Royal Highness, the Prince Regent of Portugal and Brazil, on the village of Olivenza and the other territories yielded to Spain by the Treaty of Badajoz of 1801, and considering the restitution of these objects as one of the adequate measures to assure the good, full and stable harmony between the two Kingdoms of the Peninsula, whose conservation in all parts of Europe has been the constant purpose of their negotiations, the Powers formally pledge to make the most efficient efforts, by conciliatory means, to restitute the aforesaid territories to Portugal. And the Powers recognize, as far as it depends on each one of them, that this must take place as quickly as possible.»

The Spanish Plenipotentiary, D. Pedro Gomes Labrador, refused to sign the Treaty of Vienna of June 9th, 1815, and registered a protest against several of the Congress resolutions, including the restitution of Olivenza. 
Spain finally accepted this treaty on May 7th, 1817, when Count Fernan Nuñez signed it, recognizing the Portuguese rights to Olivenza and committing to its restitution, which has not been fulfilled to this day


Brief Bibliography of Olivenza
Abrantes, Ventura Ledesma - O Património da Sereníssima Casa de Bragança em Olivença, Lisboa, Edição de Álvaro Pinto (Revista Ocidente), 1954.
Alberty, Ricardo Rosa y - A Questão de Olivença, Lisboa, 1960.
Alberty, Ricardo Rosa y - O Problema de Olivença (Desfazendo Equívocos), Lisboa, Amigos de Olivença, 1969.
Azevedo, Pinheiro de - Olivença Está Cativa pela Espanha: Por Culpa de Quem?, Lisboa, Básica, 1982.
Luna, Carlos Eduardo da Cruz - Nos Caminhos de Olivença, Estremoz, 1994.
Oliveira, Flórido José de - Breve Comentário à Sempre Viva e Actual Questão de Olivença, Lisboa, 1948.
Olivença. Terra Portuguesa, Lisboa, Grupo dos Amigos de Olivença, s/d.
Olivenza. Antología Esencial. Elementos para su Historia, (Colectânea organizada por Luis Alfonso Limpo), Mérida, Editora Regional de Extremadura, 1994.
Pereira, António Manuel - A Terra Portuguesa de Olivença, Porto, 1968.
Sequeira, Gustavo de Matos e Junior, Rocha - Olivença, Lisboa, Portugalia Editora, 1924.
Veiga, S. P. M. Estácio da - Gibraltar e Olivença - Apontamentos para a História da Usurpação destas duas Praças, Lisboa, edição de Mário Relvas, 1967.
Veloso, Queirós - Como Perdemos Olivença, 2ª edição, Lisboa, Academia das Ciências de Lisboa, 1939.
Vicente, Ana - Portugal Visto pela Espanha. Correspondência Diplomática 1939-60, Lisboa, Assírio & Alvim, 1992.