The Gts 2x3/3 was a heavy narrow-gauge locomotive for a gauge of 1,000 mm in Mallet construction and with six coupled axles. In fact, only one of the 20 locomotives that Henschel built for the Heeresfeldbahn during the First World War carried this designation. This one locomotive was bought by the Bavarian State Railways after the end of the war and used on the Eichstätt-Kinding route.

In addition to the high weight of more than 50 tonnes, the locomotives were characterized by the fact that, in contrast to many narrow-gauge locomotives of the time, they already had a superheated steam engine. With the relatively large reserves of 1.5 tonnes of coal and 4.5 cubic meters of water, it was possible to run for longer periods without refilling. In order to further improve the curve running characteristics of the chassis, the middle axle of each of the two chassis groups could be shifted 15 mm to the sides.

The use of the 20 built locomotives at the Heeresfeldbahn explains the fact that they were scattered over several countries after the end of the war. Some were also used on the Hijaz railway from Damascus to Medina. In the post-war period, the example taken over by Bavaria was used on the aforementioned route and was designated 99 201 by the Reichsbahn from 1925. After the line was converted to standard gauge in 1934, the locomotive became superfluous and was scrapped. In the years 1925 and 1928, a locomotives was built for two narrow-gauge railways in Baden. These were only designed as saturated engines and remained in use until 1957 and 1967 respectively. One of these was later used in Switzerland and can now be seen in the museum there.