The Marstrand cannon is a medieval naval cannon that was found in 2001 on the seabed off the coast of Marstrand, Sweden.

The cannon was found by an amateur diver at a depth of 20 meters. The cannon was in poor condition, but it was still recognizable as a cannon. Recent research has shown that the cannon dates from the 14th century. This makes the Marstrand cannon one of the oldest artillery pieces ever found in Europe.

MS Fr. 2643, Folio 72r

Battle of Sluis 1340. This was the first major battle between France and England in the 100 Years War. There are no firearms on board yet. (miniature 15th century) The ships depicted are of the hulk type.

There are few depictions of naval battles from the period. It is the period of the Hanseatic cities and the very beginning of guns on ships.

Harley 1319, f. 18

The fleet of king Richard II in 1319. On a miniature made ca. 1400)

Research
An international research team led by Staffan von Arbin recently examined the cannon. The cannon was part of the ship, not a cargo or ballast ship that was wrecked in the 14th century.

Specification
The cannon is made of bronze. The exterior is heavily corroded

The length was 47.5 cm. The gun consists of a 27 cm powder chamber and a 20.5 cm barrel. The weight in its current form is 18.7 kg.

Dating
Without environmental finds and/or inscriptions, cannons can only be roughly dated. A piece of textile was found in the cannon. Organic material can be dated using the radiocarbon method.* The outcome of the analysis gave a date somewhere between 1300-1400 AD.

Photograph of the bore of the barrel, showing the presumed remains of a cartouche in the mouth of the powder chamber. The mouth is 4.5 centimetres in diameter. (Staffan von Arbin)

Cartridge
A piece of textile was found in the mouth of the powder chamber. This comes from a cardouse. A cartridge is a bag with a measured load of powder in it. Preparing powder in advance in a standard size bag has many advantages for final use.

• Staffan von Arbin, Kay Douglas Smith & Tobias B. Skowronek (2023).
  The Marstrand Cannon: The earliest evidence of shipboard artillery in Europe?,
  The Mariner's Mirror, 109:3.
  pp 260-282.