Several of the key military powers of mainland Europe operated some form of armored train during World War 2 (1939-1945). The concept was a proven one, stemming from experience gained in the armored trains of World War 1 (1914-1918) decades earlier. The Germans, Soviets, and others all exhibited some form of armored train in the follow-up conflict with the two listed powers taking the capabilities of such implements to heart. Modernization efforts of the 1930s produced a whole new generation of armored trains to serve the Soviet Union with the most powerful of these becoming the "MBV-2" series. Only two were built at the Kirov Plant (Leningrad) from the period spanning 1936 to 1937.
Armored trains offered battlefield value in that they could carry considerable firepower and be quickly (and relatively economically) constructed over an existing railway car. Length of the train could vary based on design and mission need and weaponry was equally variable, largely dependent on existing stocks of howitzers / field guns. Locomotives and support cars were devised as were dedicated anti-aircraft cars and "artillery wagons" to best suit the role with extensive armor plating added where possible. Local defense from infantry and aircraft attack was through machine gun set upon trainable mountings.
The completed MBV-2 trains were massive offerings showcasing now fewer than three complete turret installations and multiple machine gun ports. A pyramidal structure amidships formed something of a command tower jutting out of the angled, armored hull. This hull was simply fitted over the existing train car. Unlike other armored trains seen prior, the MBV-2 included its own powerpack - a diesel engine mated to a hydraulic transmission system - which allowed a self-propelled quality and negated use of a dedicated locomotive. Throughout its career, the value of the MBV-2 was such that its armament was progressively updated - its original 76.2mm KT-28 guns / turrets pulled from expiring T-28 Medium Tanks were replaced by the newer, more potent, 76.2mm L-11 / F-34 series guns taken from T-34 Medium Tanks.
In practice, MBV-2 trains were generally deployed as ranged fire support weapons and as deterrents along key fronts. Its firepower was capable of stopping all known light- and medium-armored German tanks of the war which made German warplanners take their threat seriously. However, the MBV-2 trains suffered from what other armored trains suffered from - they were confined to existing railroad networks and weighed down by their heavy armament, ammunition, and armor. Fortunately for the Soviets, the country managed an extensive railway network - its value already proven in the First World War. Additionally, if disabled for any reason, these trains could also serve in a valuable static defense role. At least one (the second) MBV-2 armored train was present along the Leningrad Front where it served as part of the 14th Independent Armored Train Battalion (23rd Army). This example was saved from the scrap heap following the war to find sanctuary as a showpiece of the Kubinka Tank Museum.
In the early stages of the German invasion of the Soviet Union, the Soviets suffered mightily in their armored train numbers so much so that a new building initiative followed in later 1941. Many trains managed to serve up until the end of the war in 1945 but by this time their tactical value was much reduced due to the value added from Self-Propelled Gun (SPG) vehicles fighting on land alongside combat tanks and infantry - these vehicles were far more flexible than their train counterparts. While the armored train as a military weapon continued in service during the years that followed the war, its value was such that little effort was taken in advancing their type. They proved much more useful in third world regions with established rail networks - as proved the case with the French in Indochina. Improvised armored trains have also appeared in somewhat recent conflicts though none of a standardized design.
The MBV D-2 is another class of armored train featuring an armored superstructure though only a twin turret layout (one mounted fore and the other aft). This vehicle, not to be confused with the MBV-2 of this article, was a dimensionally smaller armored train with some examples used by NKVD Border Guards (forerunner to MVD secret police) during World War 2.