Connelly, a professor of modern British military history at the University of Kent, told History Extra the advert “confuses people about why the war carried on”, and spreads the overly-simplistic idea that young men were forced to fight.
Discussing the television advert, which has been viewed more than 12 million times on YouTube and has split public opinion, Connelly said: “The advert does not help people to understand what really happened – it confuses people about why the war carried on.
“Too much emphasis has been placed on the Christmas truce. If there was so much love in 1914, then why did the war drag on for four more years? We have overladen the truce with sentimentality, but in reality it was just a day off [for troops].
“In the days after the truce you saw troops furiously working on their defences. They took advantage of the few rain-free days over Christmas to move equipment, and unload rail wagons. You wouldn’t have known there was a truce.
“So the advert is accurate, but for very few soldiers. It is a snapshot presented as a panorama. In reality, the truce can be localised to just one or two battalions.
“There is still an incredibly moving story there – people did truce and fraternize. But this advert perpetuates the idea that that was the whole story, and any professional historian would tell you it wasn’t.
“The advert also perpetuates the idea that young men were forced to fight – that is too simplistic.”
Discussing the truce, which saw both British and German troops engage in a temporary ceasefire lasting from Christmas Eve through to Christmas Day, Connelly said: “What’s interesting is how often the truce is presented as something that the Germans started – this has become the entrenched view. It’s thought that if snobby, upper class British officers had their way, no one would have come out of the trenches. But in the advert, it’s the British soldier who first goes out. So it’s a slight variant on the usual perception of the truce.
“And of course, the advert had to feature the football match! There is no categorical evidence that a match actually took place, although we have plenty of circumstantial evidence. That iconic idea of lots of chaps playing football – a 30 vs 30 – is an idea that has grown in the public imagination.
“There was a flurry of activity about the truce in the immediate aftermath, but by the spring of 1915 it had drifted out of the public consciousness, and stayed out for quite a long time. Few post-war books talk about it, and you have to work hard to find reference to it in the 1920s and 30s.
“It wasn’t until the late 1950s/early 60s that it was really talked about again. There was a shift in perception in the 60s towards thinking that it would be apocalyptic if war happened again.
“Meanwhile, the rehabilitation of West Germany as part of a bulwark against Communism lent itself to idealising a moment when young Germans and young Brits forgot their differences. Britain started to ‘like’ West Germans again – after all, Germans were not Nazis in 1914 – and we started to perceive them as more gentle and genial – more like us. We were therefore able to think more sentimentally.
“As shown in Oh! What a Lovely War (1969) the focus moved to the futility of war – a belief that the wrong sorts of people were forced to kill each other. The Christmas truce lends itself to that agenda.
“Wilfred Owen was incorporated into the O level English syllabus in the 1960s – this helped to buttress the sentiments behind the popular understanding of the Christmas truce emerging in that decade. This meant that by 1981, when Malcolm Brown produced Peace in No Man’s Land for the BBC – a remarkable piece of television in which he interviewed veterans who witnessed the Christmas truce – there was a real dominance of the idea of ‘lions led by donkeys’, and of the innocence of the men at the front.
“And in the 1970s came a slew of books about peoples responses to the First World War, many of which perpetuated myths of the conflict. So by the 1980s there had emerged a new perception of the First World War – that it was a war in which young men were forced into conflict.”
Connelly added: “It would frustrate me if the Sainsbury’s advert confirms to people what they think they know about the First World War. But if it helps people to get interested in the conflict, and encourages people to find out more, that’s wonderful.”
On its website, Sainsbury’s says: “While our ad is a fictionalised version of the events that took place, we’ve made every effort to ensure that the details are as authentic as possible.
“We’ve worked closely with the Imperial War Museum archives, with the [Royal British] Legion and with military historian Taff Gillingham throughout. Every aspect of the production, everything from the depth of the trenches to the insignia on the uniforms is historically accurate. Even the hard biscuit we see the British soldier eating was baked to the original recipe.
“The ad launched on November 12th and we hope it will help raise further funds for The Royal British Legion.”
To watch a video about the making of the advert, click here.
And here you can watch the advertisement: