B-17 bombing the wrong side of the fronline
22 February 1943, Tunisia, late stage of the Kasserine battle:
The hide-and-seek weather also hamstrung Strategic Air Force. Out of the missions airborne, three returned their bombs, and a wandering formation of B-17's, lost in the clouds, strayed 100 miles north and bombed friendly
Souk-el-hba.
Source:
http://www.ibiblio.net/hyperwar////AAF/II/AAF-II-5.html