The fierce globe spanning campaigns saw Europe ablaze from 1939 until 1945. This is the setting for the WWII product line of Trains of War.
With the rail lines being the lifeblood for all nations, an unwritten rule for the majority of the war was limited warfare on the rail lines. History tells many a tale of armoured trains switching sides several times as forces moved back and forth across critical lines of logistics. As each side took control, the trains often came with a full compliment of armament and ammunition. Given the colossal effort of re-fitting guns with those common to your forces, some would see this as foolish however given that commanders would optimistically have control of the armoured beast again in a few hopeful weeks then it was deemed better to leave them intact then have them destroyed.
Unlike the modern militaries of today, armoured trains are considered to be unique construction processes and barely any two were alike. Basically, they were rolling carriages retro-fitted with plate steel. Open spaces, with armour flanks, were often fitted out with conventional weaponry such as anti-aircraft, mortars and small~medium artillery pieces. As the war advanced, more modern tank turrets were sourced and mated to hard points.
The WWII product line is available the Trains of War shopfront.