I’ve drawn the data for this, with permission, from Don Kindell’s excellent work at naval-history.net.
Some things to note:
1) The data behind this graph isn’t perfect. I’ve searched Don’s lists in a regrettably untechy fashion by importing them into Word and using ‘find’. For me, the advantage of this was that I didn’t have to learn how to programme. It also made me realise that any programme I’d written at the start would have missed all sorts of nuances in arrangement – so when I _do_ learn to programme, it’s important to remember that I need to be familiar with the data before I try to sort it. These figures are roughly comparable to those produced by a year ly search on the CWGC website. On the lack of perfection – the categories above are rather fuzzy in terms of whether they could be related to enemy action. ‘Killed’ is sometimes applied to those who died in training accidents, Missing Presumed Killed includes those who fell overboard and were not recovered, and in Died I have included those who fell victim to injury and a combination of sickness AND wounds. In rough terms, however, I think it would be safe to assume that Killed, MPK and D(ied) O(f) W(ounds) indicate the change between battle casualties in different months.
2) Don’s lists also include the casualties of the Canadian, Australian, Indian, South African and New Zealand navies. I have calculated these separately and taken them out for the purposes of this graph. I can post a graph of all if necessary. Nevertheless, there are some casualties who have slipped through the net (for example a very few US officers serving with RN ships). I have not taken out the figures for Royal Marine Commandos serving ashore, which probably bump up the curve of casualties in the last year of the war.
3) I think the full utility of this graph will only be apparent when it is combined with the army, RAF and civilian equivalents. It does show something of the character of the naval war however: relatively few big ship actions combined with an ongoing attritional campaign, and heavier casualties when the Navy went to the aid of the army in France, Greece or Crete.