Hold The Fort was one of the English language songs printed in the songbook “Canciones De Las Brigadas Internacionales" produced by the famous German singer Ernst Busch to enable the International brigaders to sing each others songs during the Spanish Civil War. It was published in 1938 in Barcelona.The lyrics given in Canciones de Las Brigadas Internacionales are the same as the first three verses given above by Joe Offer from The People’s Songbook. There are lots of performances of the song on Youtube