The problem is the letter i in Russian: There used to be two letters, one looking like i and the other looking like a vertical reflection of the letter N (written like u in handwriting). They sound absolutely the same. There is exactly one pair of words in the [Classical] Russian language that are distinguished by the choice of i, and these are mir and mi(u)r. After the revolution, the letter i was replaced with the u, so both words got mapped into the same spelling.

Mip means world, or society
Mup means peace

(the letter p is Russian for r)

So Voina i Mir (meaning War and Society) got mistranslated into War and Peace.