British Hand Grenades of the Great War – The Mills Bomb

It would be remiss of me not to include the ubiquitous Mills Bomb in this series of posts about Great War hand grenades, although I am not a collector of British grenades per se, and wouldn’t pretend to know as much about them as perhaps I do about those of some other nations.  So just the basics this post, illustrated by the two examples I own, interspersed with some pictures of grenade production, preparation & training. 

The Mills grenade, to give it a more proper title, was produced in huge quantities during the Great War, and, to people of my age, is probably the first thing that comes to mind when the word ‘grenade’ is mentioned.  Some sources say 50 million, others over 70 million; apparently far more of these were made than all other Allied Great War grenades put together.  How does anyone know that?  How exactly did they work it out?  Anyway, the point is, lots were made.

As we have seen in previous posts, during the early years of the 20th Century armies across Europe had, in general, failed to foresee the need for hand grenades in any upcoming hostilities, and so, soon after the outbreak of the Great War, the British War Department contacted a certain William Mills (seen here on the left, and on the right alongside the lanky Martin Hale, designer of the Hale Rifle Grenade), with the object of designing and producing a hand grenade.  Mills, the son of a Sunderland shipbuilder, was an ardent inventor who, in 1885, had opened the first aluminium foundry in the United Kingdom on the Tyne coast,…

…where he produced, among other things, one of the earliest aluminium golf clubs manufactured in Britain (diagram above, and a similar Mills club on the right).  Mills also had a company in Birmingham which produced castings for the automobile and aircraft industries, and it was here, following the approval of his design for a cast iron bodied fragmentation hand grenade (actually based on a pre-war Belgian design), that, in May 1915, production of the Mills Grenade No. 5 Mk. I began.

The predominantly female workforce of the Mills Munitions Factory in Bridge Street West, Newtown, Birmingham, line up for a staff photo.

And this is Mills’ creation, the diagram from Major Graham M. Ainslie’s 1917 ‘Handbook on Rifle & Hand Grenades’,…

…with the rifle grenade version – not from the same handbook – on the right.  Different versions of Mills grenades were produced during the Great War but essentially there was the original No. 5, followed by the No. 23, which replaced it in early 1917, and the No. 36, introduced in May 1918 (and various Marks of each),…

…and as far as I can ascertain, one of only two differences between the models were the base plugs, the body shapes being seemingly identical*; the No. 5 on the left, No. 23 in the centre, and the No. 36 on the right.

*there is argument over this.  The only other example I own for comparison is the relic below.  Identical shape?  You decide.

Incidentally, according to the Royal Armouries, and they should know, the fragmentation segments, like so many Great War grenades, often failed to shatter as they were designed to, but on the other hand, did provide a firm grip in a waterlogged trench.

The No. 23 base plug (and later the No. 36), could be fixed to a rod enabling the grenade to be fired from a rifle, as seen here in the inset, with the hole for the rod in the centre clear on my example in the main picture.  However, this didn’t in any way prevent the grenade from being thrown by hand, and as there was no point whatsoever in making two different base plates, this one duly replaced the earlier one completely (making, I suspect, collectors pull their hair out, all Mills base plates and Mills grenades being thus interchangeable).

So here are the external working bits, viewed from above, the large screw, when removed,…

…allowing ladies like these to fill the grenades with explosives (Baratol, a mixture of TNT, barium nitrate and a little paraffin wax), using the ladles and funnels seen here.

Right in the centre, above the screw, what looks like the head of a nail,…

…when removed,…

…is actually the head of the firing striker, as the diagram refers to it, enclosed in its spring, the head shown again top right, the striker end shown beneath.

Diagram showing the striker and spring in position, and if you look at the head of the striker, note how it slightly overlaps what is referred to in both diagrams as the striker lever, but we, for clarity’s sake, are going to call the handle.  We shall return to the cutaway picture in a moment,…

…because it is actually the handle that is the second difference between different versions of the Mills bomb; various types were used in the early days of the grenade, as the picture above left shows, and not all were interchangeable (earliest example at the top, the flat-stamped example at the bottom becoming the norm as the war progressed).  The centre shot shows the aluminium centrepiece (some were brass), within which the fuse & detonator (right) were contained, at which point a check of the cutaway picture will show both centrepiece and fuse in position within the grenade.

Piles of centrepieces and grenade casings (left), and a disassembled Mk. 5 (right).

If you first familiarise yourself with the handle (centre, detached), and then look at it in situ on the left, you can see that the head of the striker overlaps the end of the handle as shown in the diagram, and at the top of the same picture, the safety pin holds the handle flush with the side of the grenade.  Therefore removing the safety pin frees the handle, but as long as you still hold the handle tight against the side of the grenade, all remains safe.  Once thrown, the handle, no longer secured, flies off, the striker, its spring now released, strikes down on the cap of the fuse inside the centrepiece, beginning the five-second delay (some sources say four, not five – apparently originally seven), after which the thing explodes.

Early strikers were completely solid, which was found to impede air-flow inside the grenade once the fuse was burning, so a vent was added at the end of the striker (above left); the example on the right is probably the same, its condition making it look more like the early version.

A short extract from a Signals Corps training film taken in the summer of 1918, showing how to prepare and throw the grenade.  Note the base cap, the same as on my example, much easier to screw into the grenade by hand, and by this time used universally.

Stages in the manufacture of Mills Bombs.

Checking and then packing the finished product into transport boxes.

Photographs from the Mills Grenade Training Manual.  Mills hand grenade throwing technique from the open (above) and from a trench (below).

Mills rifle grenade training, firing from shelter (above), and firing whilst kneeling, standing and from the hip (below).

1917 photograph of a Leicestershire Regiment Bombing School officer with an array of British ordnance, his arm resting on a Mills Grenade transport box containing a dozen grenades, the label of which, pictured below, gives instructions on preparation & use.

The grenade was delivered with the centrepiece inserted but devoid of the fuse, twelve of which were supplied (right) in a tin in the same box,…

…and needed to be inserted manually before use, which is exactly what these French & British soldiers are doing, Mills transport boxes visible in both shots.

Field maintenance; topping up with explosive (left), and here’s a bunch of grenades, mate (right), hope you’ve got something to put them in,…

…which is why troops were supplied with either a waistcoat-type arrangement or canvas bucket containers (centre top), both also to be seen in the photographs.

By the war’s end, there were dozens and dozens of different contractors producing Mills grenades under licence – the ‘M’ on my example, incidentally, is simply one of those manufacturer’s marks – and the Mills was so successful that it would probably become more associated with the Second World War than the first.  Which is about where we came in.

Hard-core grave of Lieutenant Douglas Boyd Carpenter (inset), Royal Engineers, before he was moved to Delville Wood Cemetery after the war.  Boyd Carpenter was twenty eight, and was killed in action on 29th August 1916.

William Mills was knighted in 1922 for his service during the Great War.  When he died ten years later, at the age of 76, he maintained that, despite receiving a considerable sum from the British Government for his Mills Bomb invention, he had actually lost money on the project as a whole.  A true capitalist to the end.

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4 Responses to British Hand Grenades of the Great War – The Mills Bomb

  1. Nick Kilner says:

    Fantastic post, with some very nice examples. Love the video, looks like they were dropping them a little close for comfort though I’d say!
    I can’t remember if I’ve mentioned this before, but Trago Mills in Cornwall, originally a gunpowder factory, was repurposed for filling Mills bombs during WW1.
    I do find the claim that they didn’t fragment well to be somewhat curious, it’s rare to come across large chunks of grenade on the battlefield, but I guess they must have tested that.

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