Hi Horizon Sunrise here.
The Christmas Truce of 1914, for me, is one of the most magical thing that happened in World War 1. Human getting along and defying higher-ups to celebrate Christmas with everyone. but as you all know... the truce didn't last. and so will this Hearth's Warming truce.
After news of the truce, both Starlight and Celestia were furious about it. They tried scaring the troops for desertion but mostly to no avail. Some generals listened and fired their revolvers in the air in No Ponies Land to signal the start of combat again, but for those who resisted, Starlight and Celestia had to personally fire the artillery guns for them to start fighting for their lives, ending the truce once and for all.
For our Lucky in this story, she did not make it to see another Hearth's Warming, she died trying to save a comrade 5 months later, leaving her children to be orphans. Altove survived until the end and told stories about Lucky to everyone. After the war, Lucky was built as a monument for the truce.
This kind of truce will never occur again, because the truce was a symptom of a young war. Every other Hearth's Warming have shed blood all over Equestria. So we remember these heroes of friendship, those who rose against the madness of the war, trusting their enemies not to shoot, to believe that Ponies aren't as terrible as the bonfire it built itself, for Hearth's Warming.
I wish you a Merry Christmas and a Happy Hearth's Warming.