The Nationalist offensive started on 31 March and Mola threatened to bomb the Basque cities and industries:"I have decided to terminate rapidly the war in the north: those not guilty of assassinations and who surrender their arms will have their lives and property spared. But, if submission is not immediate, I will raze all Vizcaya to the ground, beginning with the industries of war.". The same day the Aviazione Legionaria bombed the town of Durango, resulting in 250 civilian deaths. On 1 April the Colonel Camilo Alonso Vega captured the mountains of Maroto, Albertia and Jarindo, and the Navarrase troops attacked the town of Ochandiano and encircled the Basque troops in it. The Navarrese occupied the town on 4 April, after heavy combats and aerial bombardment. The Basque troops left 400 deaths and 600 prisoners. Then Mola, decided to stop the advance due bad weather. On 6 April the Nationalist government in Burgos announced the blockade of the Basque ports. The British government said that the blockade was effective and warned British ships not to go to Bilbao. Nevertheless, British merchants broke the blockade and entered in Basque ports. On 20 April the Nationalists continued their offensive after a heavy artillery bombardment. The Basque troops led by Major Pablo Belderraín tried to resist but the 1st Navarrese Brigade led by Colonel Garcia Valiño broke the front and occupied Elgeta. The same day the Legion Condor bombed Guernica. The Basques retreated to the Iron Belt line and the Legion Condor bombed the roads and woods with incendiary bombs. Then, the Lendakari, Jósé Antonio Aguirre, decided to assume the command of the Basque troops, due to the incompetence of Llano de la Encomienda. On 30 April the Italians occupied Bermeo, but the Republican battleship Jaime I, was damaged by a mine. As the Nationalist troops approached Bilbao, the autonomous Basque government made an international plea to save the children of war flocking to the city. More than 20,000 were evacuated to 'temporary' safety on chartered boats, most of them to permanent exile. The fall of Bilbao The Republican government tried to send fighters to the Basque country across France, but the French government returned the aircraft after confiscating their machine guns. The commander of the Spanish Republican Air Force, Hidalgo de Cisneros, decided to send 50 fighters and bombers to the Basque Country, across the Nationalist held territory, 45 reached Bilbao. Meantime,