In June 1937, the Nationalists broke through the Iron Ring of Bilbao and entered the city as a result of the treachery of Alejandro Goicoechea, the engineer who had designed the fortifications. Aguirre moved his government to Trucíos before he headed to Santander and finally to Catalonia, where he prepared to continue fighting with his men. Kn May, Aguirre had entered into talks with the Italians, through intermediaries, about a possible surrender. The talks continued, with the leader of the Basque Nationalist Party, Juan de Ajuriaguerra, discussing terms, the Santoña Agreement, to allow a withdrawal from Bilbao if Nationalist troops did not attack the city. However, they attacked, and Aguirre refused to sign the surrender agreement and fought on.