 Paraguay bought the Madsen in the 1920s and early 1930s as that country quietly girded for war with Bolivia over mutual claims to the Gran Chaco region, and it served in the Paraguayan army in the Chaco War (1932–1935).Almost 400 were on hand when the war began, and the Paraguayans bought more as the war progressed.Bolivia also fielded Madsens of the same calibre as Paraguay (7.65×53 Mauser) during the conflict.