Nevertheless, Nationalist leader Francisco Franco decided to turn south against the city of Valencia, the capital of the Republic at the time.

On 1 May, the Nationalists continued their offensive, advancing on three fronts: Varela from Teruel, Aranda along the Mediterranean coast, and Garcia Valiño in a central column moving between them through the mountains.

[9] The difficult terrain of the Maestrazgo aided the Republican forces, driving back the Nationalists with their strong defensive positions and determination.

On 13 June, Castellón fell to Garcia Valiño's corps after several days of fighting, but they were halted short of Sagunto, where the mountains of the Sierra de Espadán came close to the sea.

[12] The Nationalists were surprised by the resistance of the Republican forces, and General Alfredo Kindelán tried to persuade Franco to abandon the operation.

[13] On 5 July, Garcia Valiño attacked from Castellón, but he was stopped by the Republican forces led by Colonel Duran and General Menendez at the Sierra de Espadan.

[16] Between 18 and 23 July, the defenses of the XYZ Line, held by two Republican corps led by Colonels Ernesto Güemes and Carlos Romero, were successful in halting the Nationalist advance.

[2][4] On 24 July, the Republicans launched an offensive in the north, the Battle of the Ebro, which prevented any further assaults on the line by drawing away eight Nationalist divisions and their heavy artillery.