J C Lawrence
Okay, as this is an 18XX game, I believe that the answer is pretty straight forward, but I thought I would ask for clarification. The BGG page lists this as a 3-6 player game, but a few online stores have it listed as 2-6 players. Like I said, I don't believe that this game could be played as a 2 player and I generally trust the info posted here on the Geek, though official variants included with games are sometimes not considered official enough to list.
1856 plays 2 players perfectly well without changing any rules.