Leutnant Hanns Joachim Wolff was a World War I flying ace

Flying ace

A flying ace or fighter ace is a military aviator credited with shooting down several enemy aircraft during aerial combat. The actual number of aerial victories required to officially qualify as an "ace" has varied, but is usually considered to be five or more...

 credited with ten aerial victories.
Wolff served with FA(A) 216 until 6 July 1917, when he was reassigned to Jasta 11. He was wounded in action on 14 August, and again on 23 November. On 18 March 1918, Wolff shot down and killed his first victim, John McCudden

John McCudden

Second Lieutenant John Anthony McCudden was a World War I flying ace credited with eight aerial victories. He survived a downing by German ace Ulrich Neckel on 28 February 1918, only to be killed in action by Hans Wolff. He was the younger brother of British ace James McCudden.-Reference:...

. Wolff then steadily scored for the next two months, downing his tenth on 15 May. He and his Fokker Dr.I

Fokker Dr.I

The Fokker Dr.I Dreidecker was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918...

 were shot down the following day, most probably by Horace Barton

Horace Barton

Captain Horace Dale Barton was a World War I flying ace credited with 19 aerial victories.He originally spent 1914–1916 with the army in German Southwest and East Africa. He then joined the Royal Flying Corps in England. His first assignment after pilot's training was 84 Squadron. On 3 January...

.

Reference

Above the Lines: The Aces and Fighter Units of the German Air Service, Naval Air Service and Flanders Marine Corps 1914 - 1918 Norman L. R. Franks, et al. Grub Street, 1993. ISBN 0948817739, 9780948817731.