Before the war the German Army had started investigating the possibility of introducing a cross country truck, to be used as a carrier for a anti-balloon gun or simply as a tractor for heavy artillery pieces. Consequently they were interested when they heard of such a design, the Marienwagen, made by the engineer Hugo G. Bremer.
In June 1915 Bremer was given the go ahead. The Marienwagen cross-country lorry, produced in the Daimler factory at Berlin-Marienfelde, was a pretty complicated vehicle, that went through several re-designs and test (not all successful), and which appeared in several forms, some semi-tracked, others full-tracked, although the basis of them all was the Daimler four-ton lorry.
After the first British tanks had appeared during the later stages of the Battle of The Somme in 1916, the shocked Germans searched meet this new and unexpected threat with vehicles of the same kind. One of the first ideas (which was a desperate stop-gap measure really) was to turn the Marienwagen into a sort of tank, and an order was issued to convert ten lorries into AFVs. The order stated that these 10 AFVs were to be delivered in the end of February 1917.
The work of turning these fully tracked lorries into armoured vehicles was led by Josef Vollmer, senior engineer of the VPK, the Motor Transport Inspection Service. The aim was to substitute an armoured hull in place of the normal lorry cab and body, and armouring the engine. The lorry transmission in the Marien–Wagen was adapted to drive the rear pair of tracks, which were of rudimenary design, sprung on semi-elliptic leaf springs. The front pair of tracks were also sprung on semi-elliptics: they were used only for steering and were not driven.
The result of this work was the armoured Marienwagen, or as it was called officially Marienwagen I mit Panzeraufbau. This can be seen as the first German tank, since it was completed by the early Spring of 1917. But it was not a tank technically speaking, only tactically. It was, in fact, more of an armoured personnel carrier: it had no fixed armament, although ports were provided for the use of the crew’s weapons. (The vehicle was to be equipped with two HMGs and two 20mm Bekker AA guns, plus a flame thrower and other close combat weapons, to be used outside the vehicle.)
Officials had already in october 1916 declared that the Marienwagen was not suitable to be used as a AFV, but work continued despite this. (Also, the Prussian War Office pressed ahead with the work on setting up on setting up the very first armoured units of the German Army, the ancestors of the famed Panzer Divisions!: Sturm-Panzerkraftwagen-Abteilung 1 and 2).
A Marienwagen with a mock-up armoured superstructure was to von Hindenburg, Ludendorff and other members of the General Staff at Mainzer Sand on 11 March 1917. It was a disaster. (It was underpowered, and because of its height it also had a very high centre of gravity, of course making it very prone to toppling over.) The generals were very disappointed with what they saw, and as a result, Ludendorff lost all interest in further German tank development. Without his interest and support the whole area was left to "quarrels and rivalries of subordinate authorities" (Hundleby and Strasheim), with the effect that the further development of German tanks were much delayed. And the whole plan of using the Marienwagen as an AFV was finally scrapped.
Later on, as a private venture, a semi-tracked version of the Marienwagen (for which a much more satisfactory type of rear track had been developed) was fitted with the armoured hull and turret of an Ehrhardt armoured car. This was only an experimental vehicle, but is interesting in foreshadowing the impressive development by the Germans of armoured halftracks in WW2.