The Mark I Medium Tank was the first British tank to be designed after World War I. Originally known as Light Tank Mark I, this tank was later reclassified as a medium tank.
Built by Vickers, the Mark I Medium Tank was the first British tank with a turret that could rotate all the way around and gears for raising and lowering the main gun, which was a 3 pounder. Close support tanks had a 3.7 inch (94 mm) howitzer.

Four Hotchkiss machine guns were carried in the turret. There were two Vickers machineguns mounted on the sides of the hull.
The Mark I Medium Tank weighed 12 tons (12,192 kg) and had a spring suspension, which enabled it to move faster than earlier British tanks – up to 15 miles per hour (24 kph). It had a 90 horsepower Armstrong Siddeley V-8 engine, which was air-cooled.

The tank held five crewmembers – a commander, a driver, two gunners and a radio operator.
Mark I Medium |
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|---|---|
| Active: | 1924 |
| Crew: | 5 |
| Weight: | 12 tons (12,192kg) |
| Length: | 17ft 6in (5.33) |
| Height: | 9ft 3in (2.82m) |
| Width: | 9ft 2in (2.79m) |
| Weapons: | Main – 3 pounder 1.85in (47mm) gun, Secondary – 2 x 0.303in (7.7mm) Vickers machineguns and 4 x 0.303in (7.7mm) Hotchkiss machineguns |
| Armor | Maximum – 0.315 in (8mm) |
| Engine: | Armstrong-Siddeley V8 gasoline, 90hp |
| Speed: | 15 mph (24kph) |
| Range: | 150 miles (241 km) |