The KPA was organized into a mechanized combined arms force of ten divisions, originally numbering some 90,000 well-trained and well-equipped troops in July, with hundreds of T-34 tanks. However, defensive actions by US and ROK forces had delayed the KPA significantly in their invasion of South Korea, costing them 58,000 of their troops and a large number of tanks. In order to recoup these losses, the KPA had to rely on less-experienced replacements and conscripts, many of whom had been taken from the conquered regions of South Korea. During the course of the battle, the KPA raised a total of 13 infantry divisions and one armored division to fight at the Pusan Perimeter.