 He was the brother of Chief of the Army, General Carl August Ehrensvärd (1892–1974) and Deputy Director of the Ministry of Defence Augustin Ehrensvärd (1887–1968).His great-grandfather was the fortress builder Augustin Ehrensvärd, his uncle was Albert Ehrensvärd and his cousin was Archibald Douglas.He became a sea cadet in 1898 and was commissioned into the Swedish Navy as an acting sub lieutenant in 1904 after passing the naval officer examination.