Olaus Charles Wilhelm Johnsen[note 1] DFC (25 October 1889 – 20 April 1960) was a British flying ace of the First World War credited with five aerial victories.
[2] Johnsen was commissioned as a supernumerary second lieutenant in the 4th London (Howitzer) Brigade, Royal Field Artillery, a unit of the Territorial Force, on 17 May 1913,[3] and was absorbed into the establishment on 17 November.
[note 2][8] Johnsen's first victory came on 11 July 1918, by driving down out of control a Pfalz D.III over Don.
[10] Johnsen relinquished his temporary rank of captain on 3 December 1918,[11] and was transferred to the unemployed list of the RAF on 2 January 1919.
[12] He resigned his army commission in the 4th London Brigade on 17 November 1920, but retained the rank of captain.