The Santoña Agreement or Pact of Santoña was an agreement signed in the town of Guriezo, near Santoña, Cantabria, the August 24, 1937, during the Spanish Civil War, between politicians close to the Basque Nationalist Party (Partido Nacionalista Vasco or PNV), fighting with the Republican Side, and Italian forces fighting with the Francoist side.
During the Battle of Santander, the Francoist troops pierced through the Republican defense lines. The Republican troops, including the Basque army, retreated to the west in a disorderly fashion, with numerous desertions.
After the fall of Bilbao, practically all Basque territory had fallen into Franco's hands. Juan de Ajuriaguerra, then president of the Biscay Regional Council of the Basque Nationalist Party, negotiated with the Italian army command a surrender agreement. The PNV offered to surrender the Basque army in exchange of its prisoners being treated as POWs under Italian commandment, and PNV members being allowed to go to exile in several British ships.
The Basque nationalists units of the Republican army in the Basque territory, fighting under the direction of Basque president José Antonio Aguirre, met at Santoña, and surrendered to the Italian forces on August 24. When news of the agreement arrived to his headquarters, Franco cancelled the agreement and ordered the immediate jailing in Santoña's El Dueso prison of the 22,000 soldiers captured. Three months later, around half of them had been freed, the other half remained in prison, and 510 were sentenced to death, a lower reprisal level than registered elsewhere. Ajuriaguerra, the highest rank in the PNV, was released from prison in 1943.
The agreement was carried out by the PNV behind the Republican government's back. For this reason, it is also known as the Santoña Treason.