Complex sentence: On 16 February 1942 north of Crete, in the Mediterranean, "Thrasher", after attacking and sinking a supply ship, was itself attacked, and later after surfacing, two unexploded bombs were discovered in the gun-casing.
Split into simpler sentences: On 16 February 1942 north of Crete, "Thrasher", was attacked after sinking a supply ship. After surfacing leter, two unexploded bombs were discovered in the gun-casing.