Guillermo Sánchez Boix, who signed his most popular work with Boixcar, is considered one of the grandmasters of Spanish comics. He started his career in the mid-1940s and among his first comics are 'El Caballero Negro', 'El Puma' and 'La Vuelta al Mundo de dos Muchachos'. He became very popular through the 'Hazañas Bélicas' series, that was launched in 1948.
The comic dealt with the recent events of World War II, emphasizing on the human values that arise due to the desperate situations that are caused by armed conflicts. The success of the series led to the launch of a second title, Hazañas Bélicas Extra. Boixcar also cooperated on collections like Mundo Futuro, Flecha Negra and Murciélago. Much of his work was reprinted in French pocket books.