Lieutenant Harold Koch Boysen was a World War I flying ace credited with five aerial victories.

[1][2] Boysen joined the Royal Flying Corps in June 1917.

After training, he was assigned to 66 Squadron to fly a Sopwith Pup.

He would not have any success until the unit re-equipped with Sopwith Camels and transferred fronts from France to northern Italy.

[1] Upon recovery, he then scored four more times in May 1918, including one win shared with Lieutenant Christopher McEvoy.