I feel it's fairly obvious that *generally speaking* the later you join in a war, the more likely you are to survive it.
But I wonder if we have statistics for any war, namely WW1/WW2 that state what percentage of first, second, etc year soldiers survived versus the later years.
On the other hand I feel it may also be accurate that toward the end of the war, fresh recruits will be coming up against the older more experienced troops and therefore if you joined and survived the early war, you may be more likely to survive it later on.
Thanks for any answers and insights!
Unfortunately, this question is incredibly difficult (if not impossible) to answer for a couple reasons:
As my expertise lies with Canada in the First World War, I will use that as an example of the difficulties of your question while also trying to answer it as best as I can from that perspective. Quick note on terms: “casualty” refers to dead, wounded and missing. If only referring to the dead, I will specifically use the terms “dead,” “war dead,” etc.
The number of Canadian war dead in the First World War is roughly 61,000. This number includes Canadians who served in the Royal Canadian Navy and the British flying services but does not include Canadians who served in the British army or navy or with other nation’s forces nor the Royal Newfoundland Regiment (Newfoundland didn’t became a province until 1949).
This number covers from 1914 to 1922. As per the Imperial War Graves Commission (now the Commonwealth War Graves Commission), someone was considered war dead if they died due to causes attributable to service between 4 August 1914 and 31 August 1921. Canada’s Book of Remembrance for the First World War covers 4 August 1914 to 30 April 1922 and doesn’t specify that the cause of death must be attributable to service.
Pinning down the exact number of Canadian war dead is difficult because it depends on how you define your terms. How do you define war dead? Do you go by the IWGC's dates or the Book of Remembrance's? Do all deaths count or just those attributable to service? How do you define Canadian? Anyone who served with the Canadian Expeditionary Force (CEF), anyone of Canadian origin who served in any military force? Just as these general statistics can be difficult to determine, so too are the more specific ones. To my knowledge, no Canadian historian has compiled statistics on a service member’s likelihood of death based on enlistment date. It would be a massive undertaking, involving going through every single service file and death record. However, I can give you a brief look at what death looked like during the war.
Service personnel could die from a variety of causes, both on and off the frontline - shellfire, small arms fire (i.e. machine guns and rifles), disease (e.g. meningitis, typhoid), accidents (e.g. vehicle accidents, kicked by a horse). The nature of fighting changed during the war, meaning that the ways men died changed too. Artillery was a major killer in the first three years of the war but improved counterbattery operations reduced artillery deaths in the later years. While most deaths happened during battles, they certainly did not only occur during battle. Even quiet periods in the frontline were marred by casualties. For example, from 1 December 1915 to 31 March 1915, a period with no major actions, the First and Second Divisions suffered about 2,600 casualties.
While all services and branches suffered casualties, men who served in the infantry were at the greatest risk of death due to serving on the sharp end. Unless they were eventually posted to a training or logistics position, infantrymen who joined the war early on were unlikely to see the end of the war without at least a wound. Tim Cook cites two revealing examples. The 1st Battalion, which served essentially the entire war, saw 6,449 other ranks (i.e. not officers) pass through its ranks - a battalion is made up of 1,000 men. The 4th Canadian Mounted Rifles arrived on the Western Front in early 1916 and only 2 officers and 34 men of the original 1,000 were still with the unit at the time of the Armistice in 1918.
As you note, however, veteran soldiers could benefit from experience and a better grasp of the frontline environment than new recruits. Time in the trenches helped men learn how to recognize the sound of shells, when to run for cover and how to navigate No Man's Land. British infantryman Robert Graves wrote of a 'sweet spot' of time served:
"[he] estimated that it took an officer about three weeks at the front to know his way around and avoid being a danger to himself. He was at his sharpest from three weeks to about six months; after that, 'he was still more or less all right, but by nine or ten months, unless he had been given a few weeks' rest on a technical course, or in hospital, he usually became a drag on the other company officers. After a year or fifteen months he was often worse than useless.'" (Cook, Shock Troops, 199)
Yet soldiers, even experienced ones, could be careless, fatalistic or just plain unlucky. One such unlucky man was Captain John A. Callum of the 28th Battalion. He fought at the Somme, won the Military Cross twice and the French Croix de Guerre and came through all that unscathed. In November 1916 he was fatally wounded when a shell hit his billets during a game of cards.
Joining the war in its later years was certainly no guarantee of a safer tour. In the last two years of the war, the CEF suffered nearly three times as many casualties as the first three years. The final major campaign of the war, the Hundred Days (8 August to 11 November 1918), cost the CEF almost 46,000 casualties. In comparison, the Somme campaign (31 August to 18 November 1916) cost a little over 24,000 casualties. The excellent encyclopedia entry on Canadian war losses by Tim Cook and William Stewart (link below) provides a detailed breakdown of casualty statistics. In a chart of the major battles/campaigns for the CEF, you can see how the casualty numbers fluctuate throughout the war and are actually at their highest in the last months of the war. These higher casualty rates are due to the large set-piece battles of 1917 and the mobile nature of warfare in last months of the war.
Ultimately, very little was certain about death for members of the CEF. I'll leave the final word to Captain D.E. Macintyre of the 28th Battalion: "such is War, full of chances."
Sources:
Tim Cook and William Stewart, "War Losses (Canada)," International Encyclopedia of the First World War, edited by Ute Daniel et al (10 August 2017) - I really recommend reading this article for more in-depth analysis and statistics on this topic
Tim Cook, Shock Troops: Canadians Fighting the Great War, 1917-1918, Vol. 2 (Toronto: Penguin Canada, 2008) - particularly Ch. 40 "The Butcher's Bill"
War Diary, 4 December 1915, MG30 E241, Duncan Eberts Macintyre fonds, Library and Archives Canada