A fork is a pole weapon

Pole weapon

A pole weapon or polearm is a close combat weapon in which the main fighting part of the weapon is placed on the end of a long shaft, typically of wood, thereby extending the user's effective range. Spears, glaives, poleaxes, halberds, and bardiches are all varieties of polearms...

 which was used in war in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 between the 15th and 19th centuries. Like many polearms, the military fork traces its lineage to an agricultural tool, in this case the pitchfork

Pitchfork

A pitchfork is an agricultural tool with a long handle and long, thin, widely separated pointed tines used to lift and pitch loose material, such as hay, leaves, grapes, dung or other agricultural materials. Pitchforks typically have two or three tines...

.
Unlike a trident

Trident

A trident , also called a trishul or leister or gig, is a three-pronged spear. It is used for spear fishing and was also a military weapon. Tridents are featured widely in mythical, historical and modern culture. The major Hindu god, Shiva the Destroyer and the sea god Poseidon or Neptune are...

 used for fishing

Fishing

Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

, the military fork was rarely barbed and normally only consisted of two tines (prongs) which were straight compared to the original pitchfork. The pair of tines usually ran parallel or slightly flared.