A knife bayonet is a knife which can be used both as a bayonet, combat knife, or utility knife as a cutting and thrusting tool or weapon. The knife bayonet became the almost universal form of bayonet in the 20th century due to its versatility and effectiveness.
The knife bayonet's widespread adoption in the 20th century was driven by its ability to serve multiple purposes: as a bayonet, combat knife, or utility knife for both cutting and thrusting.