In April 1941, a conference focused on the future of antitank operations. The immediate effect was to create an anti-tank battalion in infantry divisions, but this organic anti-tank capacity was not deemed sufficient. The conference gave broad support to the idea of creating mobile anti-tank defensive units (commanded by corps or army formations) which could be deployed to meet an armored attack. The effort stalled on the issue of which branch of the Army should control it—the infantry (as a defensive role), the cavalry (as a mobile response force), or the artillery (as heavy guns). The armored branch did not press for control of the anti-tank units, feeling that it would be at odds with their general principles of maintaining the offensive. In May, General George C. Marshall cut through the knot by declaring the issue as sufficiently important to be dealt with as a combined-arms organization, forming an Anti-Tank Planning Board headed by Lt. Col. Andrew D. Bruce, and appointing Brigadier General Lesley J. McNair to take immediate action on organizing anti-tank forces.