Upon entering the war, American field artillery had fallen behind both technically and in implementation. The initital effort was made in divisional artillery and then, in 1943, in more powerful heavy artillery to make up for the deficiencies of the air forces in close support for the troops. However, although the quality of the materiel and the shells, together with efficient training of the artillerymen were essential, numerous and efficient radio means, observation planes attached to units and artillery tractors enabled the guns to achieve maximum efficiency by allowing them to shoot rapidly and accurately, whatever the terrain and in any weather. Therefore, American field artillery was, with 300 battalionsat the beginning of 1945, the most powerful and the most modern in the world.