1943 before larger tank formations of corps size were fielded to employ armour in mass again. By mid-1943, these corps were being grouped together into tank armies whose strength by the end of the war could be up to 700 tanks and 50,000 men. Personnel The Bolshevik authorities assigned to every unit of the Red Army a political commissar, or politruk, who had the authority to override unit commanders' decisions if they ran counter to the principles of the Communist Party. Although this sometimes resulted in inefficient command according to most historians, the Party leadership considered political control over the military absolutely necessary, as the army relied more and more on officers from the pre-revolutionary Imperial period and understandably feared a military coup. This system was abolished in 1925, as there were by that time enough trained Communist officers to render the counter-signing unnecessary. Ranks and titles The early Red Army abandoned the institution of a professional officer corps as a "heritage of tsarism" in the course of the Revolution. In particular, the Bolsheviks condemned the use of the word officer and used the word commander instead. The Red Army abandoned epaulettes and ranks, using purely functional titles such as "Division Commander", "Corps Commander" and similar titles. Insignia for these functional titles existed, consisting of triangles, squares and rhombuses (so-called "diamonds"). In 1924 (2 October) "personal" or "service" categories were introduced, from K1 (section leader, assistant squad leader, senior rifleman, etc.) to K14 (field commander, army commander, military district commander, army commissar and equivalent). Service category insignia again consisted of triangles, squares and rhombuses, but also rectangles (1 – 3, for categories from K7 to K9). On 22 September 1935 the Red Army abandoned service categories and introduced personal ranks. These ranks, however, used a unique mix of functional titles and traditional ranks. For example, the ranks included "Lieutenant" and "Comdiv" (Комдив, Division Commander). Further complications ensued from the functional and categorical ranks for political officers (e.g., "brigade commissar", "army commissar 2nd rank"), for technical corps (e.g., "engineer 3rd rank," "division engineer"), and for administrative, medical and other non-combatant branches. The Marshal of the Soviet Union (Маршал Советского Союза) rank was introduced on 22 September 1935. On 7 May 1940 further modifications to rationalise the system of ranks were made on the proposal by Marshal Voroshilov: the ranks of "General" and "Admiral" replaced the senior functional ranks of Combrig, Comdiv,