We discussed earlier the genesis of the infantry-artillery combined arms team. The fruit of this marriage in WWII was the Infantry Division.
When the US was gearing up for WWII, it made a very careful analysis of the manpower likely to be available in the country. For a nation of 150 million people, it was a surprisingly small pool. In addition to manning the Army, the country had to provide for the Navy, Marines and the Army Air Forces. Less visible but just as critical were the war industries. Rosie the Riveter made a huge contribution to the war effort, but the fact of the matter is they were still outnumbered by men in industries. Some jobs such as shipfitting had almost exclusively male workforces. Farms still had to be tended. Don’t forget, at that time, almost half of America lived on a farm. The rule of thumb was that only about 10 percent of the population could be pressed into service. The Army’s share worked out to roughly 8 million men.
Given that the Army was going to have to fight outnumbered and on two fronts, it was important that the divisions it fielded be superior to the Germans they would face. One trick was standardization. The Germans had something like nineteen different organizations for just an infantry division. That doesn’t count the Panzer divisions and Panzer-Grenadier divisions (mechanized infantry). Then there was the duplicative effort of the Waffen SS divisions, which had their own organization. Instead, the Army made virtually all US infantry divisions identical in organization.
Another choice the Army made was to deliberately limit the number of divisions it created. In the Axis armies (and the British) when a division was worn down in combat, a new division was raised. But the old division still existed. Most of the casualties in a division take place in its infantry units. Instead of creating new divisions, the Army would work to keep its divisions at full strength by means of individual replacements. Since all divisions were pretty much alike, a replacement could be sent to virtually any unit.
The key emphasis was designing a division that could reasonably be expected to fight an Axis division one on one and win. Instead of the traditional rule of thumb that you should have a three to one advantage when attacking, US divisions would be expected to routinely attack with a parity in strength. The key to making this work would be a balance of size and firepower. The three infantry regiments of the division had adequate firepower thanks to the semiautomatic Garand rifle, the Browning Automatic Rifle and the machine guns and mortars organic to each infantry company and battalion. But the divisions real firepower would come from its artillery.
Each infantry division, in addition to its three infantry regiments, had a Division Artillery (DivArty) consisting of three battalions of 105mm tubes and one battalion of 155mm guns. Normally, each regiment would have a battalion of 105mm artillery firing in direct support of its objectives, controlled via Forward Observers attached to each of the regiment’s battalions. The regimental commander had a Fire Support Officer from the artillery battalion to advise him on the employment of the artillery.
The battalion of 155mm artillery was used a little differently. Its primary mission was counterbattery fire. When enemy artillery was striking infantry troops or the 105mm battalions, the 155s would locate and fire upon the enemy artillery. The division commander could also use the 155s to reinforce the fires of any of the 105mm battalions to support one of his regiments. Finally, the division commander could use the 155s (or, indeed, any or all of the 105mm battalions) to attack targets of his own.
Because of the extensive communications between the artillery and the supported infantry units, the artillery could react very quickly to calls for fire. This same tight integration with the infantry units allowed the artillery to fire on targets much closer to friendly units with less chance of fratricide.
No longer was the artillery merely acting in support of the infantry, or vice versa. For the first time in warfare, they acted in concert, combining their effects and efforts. The result was greater than the sum of their parts. An infantry division with the combined infantry/artillery team could punch far above its weight.