My great-uncle was in WWI. Ironically, his mother kept him out of the mines that had killed several of his brothers. On the last day of the war, he was in a large shell hole and wanted a smoke. No one on his side of the hole had a match, so he began making his way to a group on the other side. Half way across, a shell landed in the crater and killed everyone but him. His leg was torn open, and he spent years in a hospital recovering.
Your great-uncle was a very lucky man. One of the forgotten chapters of the Great War is the slaughter on the final day of the conflict. News of the armistice was announced the night before, along with the time it would take effect—at the eleventh hour, on the eleventh day of the eleventh month.
After making significant gains in the months leading up to the armistice (thanks largely to the arrival of American troops), the Allied high command decided to extend their lines on the final morning of the conflict. So, as the hours ticked down to the guns falling silent, thousands of American, British and Canadian troops went over the top one more time, and many paid with their lives.
Along the western front, there were a few commanders who ignored attack orders, but they were a minority. After years of battling the Germans, most were determined to gain more ground, and a better position in the upcoming peace talks. Some of the justification for the last-day attacks bordered on the ridiculous. In one case, an American general said the renewed attack was necessary because his troops lacked proper bathing facilities. The Brits saw a chance to completely re-take Mons, the Belgian city they had been forced out of four years earlier, so the Tommies went forward again.
By some accounts, more than 10,000 soldiers were killed or wounded on that final morning. The last American soldier lost in the conflict died two minutes before the Armistice went into effect.