Ley was born in Niederbreidenbach (now a part of Nümbrecht) in the Rhine Province, the seventh of 11 children of a heavily indebted[citation needed] farmer, Friedrich Ley, and his wife Emilie (née Wald). He studied chemistry at the universities of Jena, Bonn, and Münster. He volunteered for the army on the outbreak of World War I in 1914 and spent two years in the artillery before training as an aerial artillery spotter[2] with Artillery Flier Detachment 202.