 Complete the following phrase:  The half-tracks were initially unpopular and dubbed Purple Heart boxes a grim reference to the US Army decoration for combat wounds by American troops. The chief complaints centered on the complete lack of overhead protection from Air burst artillery shells and that the armor was inadequate against machine gun fire. Omar Bradley quoted in his report about half-tracks that it was a competent and dependable contrivance. Its bad name resulted from the inexperience of our troops who attempted to use it for too many things. Another major issue with the M3 was its fixed rear idler, which often broke on rough terrain. Commanders in North Africa bought parts to build spring-loaded rear idlers that could handle the rough terrain, which the Ordce Department then approved as an official fix. In 1943, the M3 served in Sicily and 