And then "the most extraordinary incident", Brockbank wrote. A cease to the firing at 2.30pm and "the Germans started shouting to us to 'come out' and 'have a drink' and also climbing about in the trenches. One of them came out in front without rifle or arms, as one of ours went out too. A huge crowd formed ... We had found a little rubber ball so, of course a football match came off and we exchanged various things ..."
Note the casual description of the object used as a football because it was not the laced-up pig's bladder which belongs to the legend of how two sides played out a game of football 100 years ago perpetuated by the film Oh! What a Lovely War, a TV advertisement by the Sainsbury's department store this Christmas and countless others in between.
Although up to 15 ad hoc matches took place along the Western Front, the evidence of an organised meeting between the British and Germans in no-man's-land to play football a century ago is thin - as a new exhibition at the National Football Museum in London reinforces.
Its artefacts include one of the best known images of the so-called Truce match - 2400km southeast of the trenches at Salonika, in Greece, when the 133rd Royal Saxon Regiment played the Argyll and Sutherlands Highlanders on Christmas Day 1915. The result: a 3-2 win for the Germans.
The evidence of an arranged Christmas Truce game is equally slim in the testimony of Private Ernie Williams, who served in the place where the game is thought most likely to have taken place, a turnip field near Messines, on the France/Belgium border where the 1st Battalion of the Norfolk Regiment and the 16th Bavarian regiment laid down arms.
Williams talks of the commanding officers ordering the men back when the fraternising started.
"One officer was shaking his hand, saying, 'Oh, bloody fools, you don't know what you are doing,"' Williams relates. "They thought it was a trap."
The doubts the exhibition raises bear out the testimony of Lancaster University's Dr Iain Adams, whose research points to ad hoc truces along 27km of British lines, though none was organised. Neither did they did start with a football and Stille Nacht on Christmas Eve.
The Argylls and Highlanders were opposite the 134th Saxon Regiment before Christmas 1914, when a nearby river flooded the trenches, forcing both sides to climb out and rebuild, less than the length of a football pitch away from each other.
"They didn't shoot at each other but started sharing tools," said Adams. "When you are working with people and are face to face, it is quite hard to shoot them."
But outside the myths, many football careers were cut short by the war. Wilfred Bartrop played three games for Liverpool before the war came and his dreams of treading the Anfield turf again were becoming real as the conflict reached its end. He died on November 7, 1918, four days before the end of the war and was the final footballer to lose his life in it.
The Christmas Truce is the soft, warm, digestible narrative of an apocalyptic conflict. The stories of Brockbank, Bartrop and countless others is its harsh reality.
Sport used to get men to the front
The ball used in a commemoration game in Messines this year. Photo / AP
Football, never backwards in claiming its part in world events, has never been too concerned about the gap between myth and reality.
UEFA has unveiled a memorial to the truce at Ploegsteert, in Belgium, and Fifa's president, Sepp Blatter, gratefully seized the opportunity too, referring in his organisation's magazine yesterday to how soldiers "laid down their guns and emerged from the trenches to play football".
But the lesser known, less saccharine story of football and WWI, tells how the sport was used as part of the propaganda effort to get men out to the front.
The Football Association's hugely controversial decision to continue the 1914-15 season when war broke out placed it under fierce attack from the British press, accused of discouraging fans from joining the troops and instead offering them football to watch.
The Times featured on the cover of the Chelsea match programme of December 5, 1914 - a goalless draw with Sheffield Wednesday - caricatured as "The Mudslingers" in a cartoon, attacking the club.
"Come on boys, keep it up, some of it is bound to stick," read the caption.
-The Independent