During the First World Word it came clear for all the fighting parties that a long bayonet that was not easy to manoeuvre was not suitable for trench war and other types of more modern warfare. This caused the different countries to develop shorter bayonets, creating in the knife bayonet.
The picture shows a knife bayonet with quillon. The quillon is a large hooked crosspiece, intended to hook and lock the opponents bayonet during the fight. In real life the quillon was not really suitable as it often got intermingled with other equipment. In addition it was not easy to produce, causing the quillonen to be a short lived invention.
Today the knife bayonet is the most common bayonet type, and is used from everything to opening hermetic boxes (sadly) to cutting of wires See AK-74.