WW1. Single handly turned the tide of the war and ended it in a year. 

WW2. Single handly turned the tide of the war and ended it in a year. 

War of Spanish Succession

Barbery wars. 

Since these wars the U.S. has been the primary force fighting in NATO or other allied groups. So while technically you can’t say the U.S. won or lost those wars absolutely none of them required anyone else to have a different outcome. 

(Ie Libya, Iraq war 1, etc)