#18 — Mark IV: The WWI Tank That Won the First Great Tank Battle
On November 20, 1917, 476 Mark IV tanks attacked the Hindenburg Line at Cambrai and advanced 8 kilometers in 12 hours — more ground than months of infantry assaults had achieved on the Western Front. It was the first mass tank attack in military history, and it proved that armored warfare could break the deadliest stalemate the world had ever known.
The Mark IV corrected the Mark I's most dangerous flaws: fuel was stored in an external armored tank instead of inside the crew compartment, and the sponson-mounted 6-pounder guns could be pushed inward for rail transport. Over 1,220 were built — more than all other WWI tank types combined. At the Second Battle of Villers-Bretonneux in April 1918, Mark IVs engaged German A7V tanks in the first tank-versus-tank combat in history. British "male" Mark IVs destroyed two A7Vs, establishing armor-on-armor combat as the future of warfare. The Mark IV's legacy in military history is straightforward: it proved the concept that the Mark I had merely introduced, turning the tank from an experiment into a doctrine.
