When the Iran was occupied in August 1941 by British and Soviet forces in order to open a save "back-door" for Lend-Lease deliveries to Russia, it happened not to the least in regard of the Iranian State Railway.
The »ISR«, as called briefly, had been built in the late 1930s primarily to connect the Persian Gulf port of Bander-Shahpur with Tehran and the Caspian Sea port Bander-Shah.
There also existed a section leading northwest to the Iranian-Russian border, but this part was not yet fully completed.
After the successful occupation, the British and Soviet forces immediately took over the control of the Railway and launched a regular transport of all sorts of supply goods.
Towards the end of 1941, as the large amount of steam locomotives became obvious, the British Government ordered 200 standard-gauge 2-8-2s from the United States, under Lend-Lease arrangements.
These locomotives were built by ALCo, Baldwin and Lima to British specifications, but were of typical American design.
In total, 91 oil-burning engine reached the Iran from October 1942 on, replacing the existing British LMS Stanier 8F, but after the arrival of the ALCo 1000hp RSD-1 diesels, during the early part of 1943, the 2-8-2s were normally restricted to the less mountainous section between Arak and Teheran.