sentences:  The First Army's units for the operation consisted of the V and VII Corps, that latter assigned for the main thrust through the Hürtgen Forest, with V Corps protecting its southern flank.For the upcoming offensive, both armies were heavily reinforced.Total strength of the First Army rose from about 250,000 in September to about 320,000 before the offensive, although only about 120,000 troops would participate in the main operation.