Here's the summary from Wikipedia, which seems to correlate with what I remember reading:

"Based at Hvalfjordur, Iceland, she sailed from Naval Station Argentia, Newfoundland on 23 October, with four other destroyers to escort eastbound convoy HX 156. At about 05:25 on 31 October, while escorting that convoy, Reuben James was torpedoed by U-552 commanded by Kapitänleutnant Erich Topp near Iceland. Reuben James had positioned herself between an ammunition ship in the convoy and the known position of a "wolfpack", a group of submarines that preyed on Allied shipping. Reuben James was hit forward by a torpedo and her entire bow was blown off when a magazine exploded. The bow sank immediately. The aft section floated for five minutes before going down. Of the 159-man crew, only 44 survived."

Charley Noble