Leonardo da Vinci, armored car concept — c. 1487
  1. 1Conical wooden + metal armor shell
  2. 2360° cannons around the perimeter
  3. 3Internal hand-cranked gear system
  4. 4Sloped sides — pre-modern angled armor
  5. 5Four wheels, ~8-man crew to power

The pitch letter

Leonardo arrived in Milan in 1482 looking for work. He sent Duke Ludovico Sforza a now-famous letter listing what he could build: portable bridges, siege machines, mortars, naval weapons, and — in point seven — "armored carts, safe and unassailable, which will enter the close-up ranks of the enemy with their artillery."

The sketch he drew shortly afterwards is now in the British Museum's Codex Arundel. A conical, wooden shell — like an upturned shallow bowl — pierced by cannon barrels around its entire circumference, mounted on four wheels, with the entire crew inside cranking a system of gears that drove the wheels. It is unmistakably a tank.

Why it is genuinely a tank, not just a covered cart

It hits every functional checkbox:

  • All-around armor: a sloped, faceted shell — centuries before glacis-angle armor became standard on T-34s and beyond.
  • 360° fires: cannons ringed the entire perimeter, anticipating modern turrets and crow's-nest secondaries.
  • Self-propelled: the crew turned cranks that drove the wheels through reduction gearing. Mechanical mobility, not draft animals.
  • Crewed combat compartment: protected fighters inside an armored hull, with vision slits and a top observation cupola.
  • Combined arms organic to the vehicle: Leonardo described the machine operating with infantry, breaking the line so foot soldiers could pour through. Modern tank doctrine in one paragraph, 400 years early.

The deliberately wrong gears (probably)

Look closely at the drive train in Leonardo's sketch and something is off: the gear arrangement would make the front and rear wheels rotate in opposite directions. The machine, as drawn, cannot move forward.

Two main theories exist. One: a copyist error or a quick draft Leonardo never bothered to fix. Two — and this is the romantic favorite of historians: Leonardo deliberately introduced the flaw so that anyone who stole the plans couldn't actually build a working tank. He was famously guarded about his most dangerous designs. Either way, modern reconstructions (notably the BBC's and Mark Rosheim's) prove that with the gears corrected, the machine works — though it is achingly slow and the human power output is wildly insufficient.

Why it wasn't built in 1487

Same wall as every pre-1900 war machine: no engine. Eight men cranking a gearbox can move a hundred kilos quickly or fifteen tons very slowly. They cannot move fifteen tons of cannon and oak across a battlefield in a way that survives contact with the enemy.

Leonardo solved the conceptual problem 400 years before the technology existed. He drew the target. The next four centuries — Hussite war wagons, steam landships, H.G. Wells' fiction, the British Landship Committee, the Holt tractor — were all chasing that same silhouette.

The lineage

Draw a straight conceptual line and it looks like this:

  1. 1487: Leonardo's armored car — concept, no engine.
  2. 1855: James Cowen's steam land battery — engine exists, but is enormous and unreliable.
  3. 1903: H.G. Wells, "The Land Ironclads" — fiction predicts the tank with eerie precision.
  4. 1916: Mark I at the Somme — all four ingredients finally fit in one chassis.
  5. 1944: T-34/85 — sloped armor (Leonardo's faceted shell, finally optimized).
  6. Today: M1 Abrams, Leopard 2, T-14 Armata — same problem, refined.

Every tank since 1916 is, in a real sense, an answer to a question Leonardo wrote down in 1487.