(military, aviation) A defensive combat tactic in which multiple aircraft form a horizontal circle in the air when attacked, so that the armament of each aircraft offers a measure of protection to the others.

Gervais Raoul Victor Lufbery (March 14, 1885 – May 19, 1918) was a French and American fighter pilot and flying ace in World War I. Because he served in both the French Air Force, and later the United States Army Air Service in World War I, he is sometimes listed alternately as a French ace or as an American ace.