Having trawled dozens of primary sources on the First World War, there is no doubt that bayonet fighting was indeed 'a thing'.

If one thinks about it, bayonets were never going to account for more than a tiny number of deaths and woundings overall in a large-scale war. It was only relevant to assaults that were successful enough to make to to a stage of hand-to-hand combat, and indeed where defenders remained. Unquestionably many of those killed with bayonets had already surrendered or were hors de combat. (There are several references to Australian troops at Villers-Bretonneux in 1918 using practised bayonet fighting methods on closing with German troops. As these were often night attacks, and involved inexperienced defenders, the bayonet was found useful as a stealth and terror weapon. These soldiers were also well known for killing prisoners or, more accurately, men attempting to surrender. There are also references and quotes by officers discussing other troops' lack of ability to fight with the bayonet, implying such skills were parts of a soldier's useful repertoire. [ref: P.A. Pedersen Villers-Brettoneux]).

Bayonet fighting was emphasised in training more as a psychological ploy to encourage soldiers to 'close with the enemy', or, to be willing to overcome his innate desire to avoid this. The British Army had a particular Scottish officer who lectured thousands of recruits on bayonet fighting, ostensibly to provide 'expert advice' but clearly in reality to impose a martial attitude to a citizen army undergoing rapid training (ref: John Ellis A Social History of the Machine Gun). Field Marshal Haig himself was among those who emphasised he 'shock value' of 'cold steel'. It was in part this misinformation and mythologising that led to a later widespread ridiculing of the bayonet as a useful weapon. Much military training centres on ensuring the soldier thinks of himself as a useful part of a fighting machine in even the most difficult circumstances: if a man can think himself as a functioning soldier when he has only a knife, he is less likely to panic when his rifle won't fire or when he has no ammunition. Even if he never has to use his bayonet, the aim is that the man thinks himself a soldier as long as he has it.

But despite being exceptional, bringing an assault to its conclusion with the bayonet did indeed occur in small degrees in many battles. For shock troops such as the Australians and Canadians, and the elite German Sturmtruppen of 1918, use of the bayonet was an important means to convince an enemy not to fight for their trench once it was entered, in set-piece battles or nocturnal raids. Perhaps more important was the willingness to use the bayonet that characterised aggressive soldiers with high morale.