The Galactic Council learn about ANZAC day -- Anon Guest
Humans are Deathworlders. They have such an enormous warrior culture that baring their teeth is seen as being friendly, and can get hostile when others fail to follow suit. Thus it is surprising to learn about assorted memorial days. War, they reason, is a common occurrence on Deathworlds. They should be as unmarked as the average rainstorm.
Then they learned about the Great Wars and the immense chains of stupidity that almost obliterated certain towns and impeded their usual lifestyles for the better part of two decades. Most of which was due to the Deathworlder habit of romanticising battle, doing things like calling it 'fun'.
The senselessness of industrialised war left an impact on the Humans of the era. So much so that mourning for the lost became a tradition. As did the tendency to keep perpetuating war. Group identities formed based on alliances in those turbulent years. Such as the newest nations of the time, and geographic neighbours, Australia and New Zealand. They lost so much, together, that they formed an unbreakable bond. Comrades in arms, a uniquely Deathworlder bond so intense that they made their own day for remembering it.