In 1937, the US armed forces bought Mack's commercial E series in small orders, the EH was the largest model.

In 1942, large numbers of modified trucks were supplied under Lend-Lease to Britain and many could be seen carrying the L or H-numbers of the British War Department.

They differed from the commercial type by lacking chrome trim and nameplates, and were fitted with a military style cargo body with canvas cover.

In 1943 a military design version of the EH type was destined mainly for Defense Aid.

[3][4] The EH had a ladder frame with two beam axles on leaf springs.

Besides the cargo and semi-tractor, there were fuel and water tankers, van bodies, wreckers, bus chassis, and fire trucks.