Detail from Simone Martini's fresco of
Guidoriccio da Fogliano at the Siege of Monte Massi in 1328 at
Scala/Palazzo
Pubblico, Sienna.
(I don't know exactly when the picture was painted, but Martini's dates
are 1284-1344, so it must have been pretty soon after the 1328 siege.)
Thanks to Bob Charrette, who found this picture.