Energetic and painstaking efforts were made by Army Ground Forces to optimize the divisions for combat operations. Non-essential troops and equipment were eliminated. The principle was established that a unit would have only the equipment that it would normally need. Other economies were also made. For example, trucks were replaced, wherever possible, by trailers. While admittedly not as useful as trucks, not only were they cheaper to produce, but they required less personnel to maintain, and less space to ship. As a result of economies, 89 divisions were active in 1945 for the same number of personnel as required to man 75 in 1943. General Douglas MacArthur pointed out that the division, while initially well-balanced, soon became unbalanced in combat as the infantry took casualties faster than other arms, requiring the relief of the entire division when most of its components were capable of further effort.