The Panzer 68 was a Swiss main battle tank developed by the Eidgenoessische Konstruktionswerkstaette in Thun in the late 1960s, and was the main tank of the Swiss Army until the late 1990s. The Panzer 68 was based on the Panzer 61, which initial development dates back to 1951. The development started immediately after the successful introduction of the Panzer 61. Improvements consisted of wider tracks, stabilized gun, and the introduction of a second machine gun instead of the coaxial 20mm gun of early Panzer 61 models. In 1968 (hence the name) the Swiss parliament decided to buy 170 vehicles. Deliveries of the Panzer 68 started in 1971. In 1977 a second batch was manufactured. In the years between 1978 and 1983, a third and fourth batch followed. The last two lots were called either AA3 and AA4 or Panzer 68/75. The most important change was the introduction of a bigger turret. The Austrian Army showed some interest in the Panzer 68 in the late 1970s, but decided not to buy the model when the deficiencies of the system became public. (Source: Wikipedia.org, CC BY-SA)