Today in WW II: 21 Jul 1944 US forces land on Guam.   

M-21 Halftrack Mortar Carrier

The M-21 Halftrack Mortar Carrier was an upgrade to the M-4 Mortar Carrier Halftrack that replaced the M2 Halftrack with the M3 Halftrack as the base vehicle. The main innovation was to have the mortar face forward making it even easier to move to a new position and fire immediately.

Production of the M21 Halftrack Mortar Carrier by White Motor Company started in January 1944 with a total of 110 vehicles produced before production was halted in March 1944.

T19 prototype of the M21 Halftrack Mortar Carrier, an upgrade and replacement for the M4 and M4A1 Halftrack Mortar Carrier
T19 prototype of the M21 Halftrack Mortar Carrier, an upgrade and replacement for the M4 and M4A1 Halftrack Mortar Carrier..

Overhead view of the M21 Halftrack Mortar Carrier with the front facing mortar and its ammunition
Overhead view of the M21 Halftrack Mortar Carrier with the front facing mortar and its ammunition.