group comprising Henschel Werke and the Swiss MOWAG company. This resulted in the production of seven prototype vehicles. A second set of eight prototype vehicles were built between 1961 and 1963. Development priority was then switched for a while to the development of the Jagdpanzer 90 mm Kanone. In 1967, after military requirements were finalized, a third and final set of ten prototypes were built. Final development work was completed by the Rheinstahl group. 10 pre-production vehicles were built and completed troop trials with the West German army between October 1968 and March 1969. In May 1969, the vehicle was named the "Marder" after the European pine marten, an agile, short-legged, bushy-tailed, medium-sized carnivorous mammal in the weasel family. In October Rheinstahl was chosen as the prime contractor. The first production Marder was handed to the West German army in May 1971. Production of the vehicle continued until 1975, with 2,136 vehicles being completed. In 1975, the Milan missile was adapted to be fired by the commander from his open hatch. Between 1977 and 1979 Milan missiles were fitted to the Marders. A number of upgrade programs were carried out, that included fitting night vision equipment and a thermal imager, as well as an upgraded ammunition feed to the 20 mm cannon. Around 1985, the designation was changed to Marder 1 (until then it was simply Marder) since a follow-up IFV was under construction. The new vehicle was supposed to be the partner of the Leopard 2, just like Marder was the companion to the Standardpanzer/Leopard 1, it was named Marder 2 and the older vehicles re-designated. The A3 upgrade program began in 1988. Thyssen-Henschel was awarded a contract to upgrade 2,100 Marder 1 A1/A2 series vehicles to A3 standard, at a rate of 220 a year. The first upgraded vehicles reached the West German army in November 1989. The modification package included: Improved armour, weighing 1,600 kg, intended to protect against the 30 mm 2A42 cannon on the Russian BMP-2. The armour provided additional protection against cluster bomblets. The hatches over the infantry compartment were rearranged. The suspension was reinforced, a new braking system was installed, and the gearbox adjusted. The heating system was replaced with a water based heating system. The turret was reconfigured. The new total weight was 35,000 kg. Description The hull of the Marder 1 is all welded steel, giving protection from small-arms fire and