Which was the first cooperative board game?
For the purpose of this question, we can define "cooperative" as "there is more than one player, and at the end of the game, they either all win or all lose".
My unsuccessful attempts to answer the question:
At the time when I am writing this, the history section on Wikipedia mentions an 'alternative ruleset' for The Landlord's game (1903) as an early example (without claiming it is the first); I could not easily google this ruleset to confirm that it fits the criterion.
Some sources cite Community (1972), but that seems quite late, given the other games mentioned on Wikipedia.
Boardgamegeek has a cooperative game category, but many of the listed games are clearly not cooperative with this definition, as their descriptions mention winning and losing teams. And there are various pages of games without a publication date in the list.