Here it is. Word of warning: It will leave you a quivering emotional wreck.
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Why is this advert so powerful?
Because this actually happened.
It began on Christmas Eve (Germans celebrate 24 December more than 25 December). As The Long, Long Trail, a historical website, tells it:
During the afternoon and early evening, British infantry are astonished to see many Christmas trees with candles and paper lanterns, on enemy parapets. There is much singing of carols, hymns and popular songs, and a gradual exchange of communication and even meetings in some areas. Many of these meetings are to arrange collection of bodies. In other places, firing continues.
The Operation Plum Puddings website, which describes the truce in detail, cites this letter from Private H. Scrutton, Essex Regiment. It was published in the Norfolk Chronicle on 1 January, 1915:
As I told you before our trenches are only 30 or 40 yards away from the Germans. This led to an exciting incident the other day. Our fellows have been in the habit of shouting across to the enemy and we used to get answers from them. We were told to get into conversation with them and this is what happened:
From out trenches: "Good morning Fritz." (No answer).
"Good morning Fritz." (Still no answer).
"GOOD MORNING FRITZ."
From German trenches: "Good morning."
From our trench: "How are you?"
"All right."
"Come over here, Fritz."
"No. If I come I get shot."
"No you won't. Come on."
"No fear."
"Come and get some fags, Fritz."
"No. You come half way and I meet you."
"All right."
One of our fellows thereupon stuffed his pocket with fags and got over the trench. The German got over his trench, and right enough they met half way and shook hands, Fitz taking the fags and giving cheese in exchange."
The chocolate bar in the advert will go on sale in branches of Sainsbury's.
In a statement, Sainsbury's said:
Sainsbury's and The Royal British Legion have sought to make the portrayal of the truce as accurate as possible, basing it on original reports and letters, as well as working with historians throughout the development and production process...
Sainsbury's is one of the biggest supporters of the Legion and waits until after Armistice Day to launch its annual Christmas campaign so that stores can remain focused on raising funds for the Poppy Appeal. In 2013 alone, Sainsbury's raised around £4.5m for the charity through hosting Legion volunteers instore to offer poppies, as well as from the sales of an exclusive range of poppy products and colleague, supplier and customer fundraising.
The supermarket has also posted a making-of video here.
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The thinkpieces on whether the ad is commercially exploitative or not are no doubt minutes away, but for now it's safe to say the advert has gone down extremely well on Twitter.
Stunning @sainsburys #Christmas ad w/ @WaddingtonRBL showing @johnlewisretail how it's really done http://t.co/ecFZBZul8v
The Sainsbury's Christmas ad is the best Christmas advert I've seen so far
Well done @sainsburys for using their Christmas ad to raise money for good cause instead of for selling cheap cuddly toys at inflated prices