The Battle of Guadarrama (Spanish: Batalla de Guadarrama, also known as Batalla de Somosierra) was the first battle in the Spanish Civil War involving troops loyal to the Second Spanish Republic in the Guadarrama Range. The battle took place in the last week of July and in early August 1936. The Nationalist side sent by General Mola was attempting to cross the mountain passes of the Sierra de Guadarrama and reach Madrid by the North, but the Republican side, made up of mililtiamen and troops disbanded by the government left Madrid to stop the Nationalists. The Republican side was successful and the Nationalist troops did not manage to cross the mountain passes.