Friedrich Karl Lütge was born into a Protestant family at the start of the twentieth century at Wernigerode, a midsized town located in the Harz Mountains between Hanover and Halle. He was the older of twin brothers. There were also two younger siblings. His father was a captain in the German merchant navy who was much involved with Kamerun trade, but died in 1905. As a child Friedrich Lütge suffered from a spinal disease which confined him to bed for three years. On 23 September 1918, while still at school he found himself recruited into an infantry regiment as a junior officer ("Fahnenjunker"), but by this time the First World War was nearly over and he was never sent into the fighting of it. However, in February 1919 he found himself taken into the "Freikorps" ("volunteer corps") of in Berlin, and he was involved in the putting down of the Spartacus uprising. It was only in 1921 that he passed his Abitur (school leaving exams) which opened the way to university-level education.