In March 1306 Ferdinand IV had requested to meet with James II of Aragon, and from that moment the ambassadors of the Kingdoms of Castile and Aragon tried to set a date for the meeting between the two sovereigns, that had to be postponed several times due to the existing internal conflicts in both Kingdoms.
The clauses of the Treaty of Alcalá de Henares, signed on 19 December 1308, had their origins in the meetings held by the Kings of Castile and Aragon in the Monastery of Santa María de Huerta and in Monreal de Ariza in December 1308.
The themes discussed in the meetings were the relaunch of the Reconquista wars, desired by both sovereigns, and the marriage of the Infanta Eleanor of Castile, eldest daughter and heiress of Ferdinand IV, with the Infante James of Aragon, eldest son and heir of James II and, finally, the satisfaction of the commitments made with Alfonso de la Cerda, which had not yet been fully fulfilled.

Regarding the marriage between Eleanor of Castile and James of Aragon, although it was celebrated in October 1319 was never consummated, since the Infante James escaped after the wedding ceremony, resigned soon after to his rights to the Aragonese throne, and entered in the Knights Hospitaller Order.
The Infanta Eleanor, years later (1329), marry with Alfonso IV of Aragon, second son and successor of James II.
Regarding the second subject discussed in the meetings of the sovereigns, Ferdinand IV gave to Alfonso de la Cerda 220,000 maravedíes that had not yet been received by him and in exchange he surrender to the king the cities of Deza, Serón and Alcalá.
The idea of re-launching the struggle against the Kingdom of Granada was enthusiastically received by both sovereigns, who had the support of King Abu al-Rabi Sulayman of Morocco, who was at war against Sultan Muhammed III of Granada.

After the meetings held between the two sovereigns, Ferdinand IV met in the town of Almazán with his mother and both agreed to clean up the area between Almazán and Atienza from criminals and destroy the fortresses that served them as a refuge, work which was made by Infante Philip of Castile, brother of Ferdinand IV.
For her part, the Dowager Queen was pleased with the agreements between her son and the King of Aragon.
Immediately after, the King went to Alcalá de Henares.

On 19 December 1308, in Alcala de Henares, Ferdinand IV and the Aragonese ambassadors Bernaldo de Sarriá and Gonzalo García signed the Treaty of Alcalá de Henares.
The Castilian sovereign, who had the support of his brother, the Infante Peter, Diego López V de Haro, the Archbishop of Toledo and the Bishop of Zamora, agreed to start the war against the Kingdom of Granada on 24 June 1309 and promised, like the Aragonese monarch, not to sign a separate peace with the Granadine ruler.
Ferdinand IV and James II both agree to contribute with ten galleys each for the expedition.
It was approved with the consent of both parties that the troops of the Kingdom of Castile and León would attack the cities of Algeciras and Gibraltar, while the troops of the Kingdom of Aragon would conquer the city of Almería.

Ferdinand IV promised to give up one-sixth of the Kingdom of Granada to the Aragonese king, and granted him the Kingdom of Almería in its entirety as advance, except for the cities of Bedmar, Locubin, Alcaudete, Quesada, and Arenas, who previously belonged to the Kingdom of Castile and León.
Ferdinand IV established that if the situation occurred that the Kingdom of Almería didn't correspond to the sixth part of the Kingdom of Granada, the Archbishop of Toledo (on the part of Castile) and the Bishop of Valencia (on the part of the Aragon) would be the ones in charge to solve the possible deficiencies of the calculation.
The granting to the kingdom of Aragon of such a large part of the Kingdom of Granada caused that John of Castile and Juan Manuel of Villena protested against the ratification of the Treaty, although their protests had no consequences.

The entry into force of the clauses of the Alcalá de Henares treaty meant a significant expansion of the future
In March 1306 Ferdinand IV had requested to meet with James II of Aragon, and from that moment the ambassadors of the Kingdoms of Castile and Aragon tried to set a date for the meeting between the two sovereigns, that had to be postponed several times due to the existing internal conflicts in both Kingdoms. The clauses of the Treaty of Alcalá de Henares, signed on 19 December 1308, had their origins in the meetings held by the Kings of Castile and Aragon in the Monastery of Santa María de Huerta and in Monreal de Ariza in December 1308. The themes discussed in the meetings were the relaunch of the Reconquista wars, desired by both sovereigns, and the marriage of the Infanta Eleanor of Castile, eldest daughter and heiress of Ferdinand IV, with the Infante James of Aragon, eldest son and heir of James II and, finally, the satisfaction of the commitments made with Alfonso de la Cerda, which had not yet been fully fulfilled.
Regarding the marriage between Eleanor of Castile and James of Aragon, although it was celebrated in October 1319 was never consummated, since the Infante James escaped after the wedding ceremony, resigned soon after to his rights to the Aragonese throne, and entered in the Knights Hospitaller Order. The Infanta Eleanor, years later (1329), marry with Alfonso IV of Aragon, second son and successor of James II. Regarding the second subject discussed in the meetings of the sovereigns, Ferdinand IV gave to Alfonso de la Cerda 220,000 maravedíes that had not yet been received by him and in exchange he surrender to the king the cities of Deza, Serón and Alcalá. The idea of re-launching the struggle against the Kingdom of Granada was enthusiastically received by both sovereigns, who had the support of King Abu al-Rabi Sulayman of Morocco, who was at war against Sultan Muhammed III of Granada.
After the meetings held between the two sovereigns, Ferdinand IV met in the town of Almazán with his mother and both agreed to clean up the area between Almazán and Atienza from criminals and destroy the fortresses that served them as a refuge, work which was made by Infante Philip of Castile, brother of Ferdinand IV. For her part, the Dowager Queen was pleased with the agreements between her son and the King of Aragon. Immediately after, the King went to Alcalá de Henares.
On 19 December 1308, in Alcala de Henares, Ferdinand IV and the Aragonese ambassadors Bernaldo de Sarriá and Gonzalo García signed the Treaty of Alcalá de Henares. The Castilian sovereign, who had the support of his brother, the Infante Peter, Diego López V de Haro, the Archbishop of Toledo and the Bishop of Zamora, agreed to start the war against the Kingdom of Granada on 24 June 1309 and promised, like the Aragonese monarch, not to sign a separate peace with the Granadine ruler. Ferdinand IV and James II both agree to contribute with ten galleys each for the expedition. It was approved with the consent of both parties that the troops of the Kingdom of Castile and León would attack the cities of Algeciras and Gibraltar, while the troops of the Kingdom of Aragon would conquer the city of Almería.
Ferdinand IV promised to give up one-sixth of the Kingdom of Granada to the Aragonese king, and granted him the Kingdom of Almería in its entirety as advance, except for the cities of Bedmar, Locubin, Alcaudete, Quesada, and Arenas, who previously belonged to the Kingdom of Castile and León. Ferdinand IV established that if the situation occurred that the Kingdom of Almería didn't correspond to the sixth part of the Kingdom of Granada, the Archbishop of Toledo (on the part of Castile) and the Bishop of Valencia (on the part of the Aragon) would be the ones in charge to solve the possible deficiencies of the calculation. The granting to the kingdom of Aragon of such a large part of the Kingdom of Granada caused that John of Castile and Juan Manuel of Villena protested against the ratification of the Treaty, although their protests had no consequences.
The entry into force of the clauses of the Alcalá de Henares treaty meant a significant expansion of the future
Ferdinand IV of Castile