I recently started examining holidays and how/if they would be established in Colony X on some distant planet. There is another American holiday in November that I haven't yet examined. It would be stretching back a bit to look at it now, but otherwise, it will be another year before I get to it, so … why not?
Veteran's Day is an opportunity to remember those soldiers who have made it possible for us to live in our version of freedom. I don't see this colony as holding over many (if any) holidays from 'the old home', as they are looking for a new beginning … their version of freedom. Likewise, I don't see them as fighting any wars to establish their colony, since the planet has no 'intelligent' natives, and the old home hasn't followed them to this planet. So I don't see any reason for them to establish a 'Veteran's Day', not for many generations. After they've grown enough to swarm over the planet and form opposing governments that inevitably go to war with each, then it might happen. On the other hand, they might have someone who stands out as a hero – someone who successfully warns them of some impending doom so that they can avoid it. That might make a big enough impression that the people – looking for an excuse to party – might decide to celebrate Brok's Day. The Americans have several of that type; Martin Luther King Day, Washington's Birthday, Lincoln's Birthday (those two now rolled into Presidents' Day) and so on.
I can't speak for all Americans, but it seems to me that for most of us, Veteran's Day is simply an opportunity not to go to work. Retail uses holidays as an excuse to have sales. Fraternal orders based on military service might have some kind of service or remembrance on Veteran's Day, but if you don't belong to one, don't have a close family member who belongs to one, you aren't likely to care. And so I see Brok's Day as developing, over the generations. After all, once the river has been dammed, removing threat of flood – or whatever Brok saved the colony from – would anybody really care? So Brok's Day, at some point during the year, to celebrate the continuation of the colony. Go, Brok!