During the Battle of Madrid in November 1936, he led the 3,000 member XI International Brigade. At a time when it appeared all was lost —the Republican government of Largo Caballero had already abandoned the capital— the arrival of Kléber and the International Brigade boosted the morale of Madrid's Republican defenders when the loyalist troops fought from street to street and held the line at Casa de Campo, repulsing the Nationalists. Soviet propaganda broadcast the 'Victory over Fascism' throughout the world and —despite General Miaja's and General Vicente Rojo's crucial role— heralded General Kléber as the "Savior of Madrid". "The New York Times" correspondent Herbert Matthews interviewed Stern shortly after the battle. "Listening to General Kléber," he wrote, "one gets the impression of great dynamic force. He is a character possibly destined to play a great part in the troubled years which face the world... In thinking about him it is hard not to ponder on the ironical fact that Hitler is not the only native of Austria who is playing a great part in the Spanish Civil War."