In 1936, when the Spanish Civil War started, he joined the Fifth Regiment.[4] The following year, as a high-ranking army officer, commanding the 11th division of the republican army, Líster was instrumental in the defense of Madrid and other important military actions. In October 1936 he led a mixed brigade in the ill-fated Republican counteroffensive at Seseña. As a divisional commander, he helped stall the Nationalist attack along the Jarama and played a significant role within the successful Republican counterattack at the Battle of Guadalajara.[5]
Líster is widely regarded as a war hero for the Republican cause. His reputation as a competent military commander is largely based on his role as commander of the "11th Division", which was involved in some of the most important battles in Guadalajara, Brunete,[6]Belchite and Teruel.[7] Those brigades under his control rapidly became special battalions which took care of special operations. Some consider examples of his high-level tactical command[dubious – discuss] as the seizure of Brunete that helped to capture the nationalist general staff with almost no casualties[citation needed] for the republican army and his surprise action in Teruel that totally confused the nationalist army.[citation needed] Beevor, however, cites 4,300 casualties out of a strength of 13,353 at Brunete.[8] Beevor quotes the chief Soviet advisor as reporting that Líster's division collapsed and 'lost its head and fled. We managed with great difficulty to bring it under control and prevent soldiers from fleeing their units. The toughest of repressive measures had to be applied. About 400 of those fleeing were shot on 24 July.' [9]
Later, he led the V Army Corps in the battle of the Ebro and in the Catalonia Offensive.[10]
The "11ª División" did, however suffer a severe setback when it failed to capture Fuentes de Ebro in the Republican offensive in Aragon in August 1937. The International Tank Regiment lost the majority of its tanks. This loss led to mutual hatred between Lister and Juan Modesto, commander of the 5th Corps (which "11th Division" formed a part of). Modesto held Lister responsible for the losses.
Lister remained defiant as late as September 1938, when defeat for the Republic looked inevitable. Lister claimed that the Nationalist forces remained entirely dissatisfied with the job Franco was doing. He stated;
"The enemy rank and file are restive and dissatisfied with the constant deceptions played upon them by Franco and with the conviction that he is incompetent both as a military and political leader."[11]
Líster wrote four books, two of them —Nuestra guerra (1966) and Memorias de un luchador (1977)— were about his personal experiences in the Spanish Civil War.
Nuestra guerra (Our War) 1966
Memorias de un luchador (Memories of a Fighter) 1977
¡Basta! (Enough!) 1970
Así destruyó Carrillo el PCE (Thus Carrillo destroyed the PCE) 1982