Chess Variants/Double Chess

Introduction
Double Chess is a large variant that uses a 12 x 16 board, with each player in control of two full chess armies.

History
Double chess was created by Julian S. Grant Hayward in 1916, but it would take until 1929 for the variant to reach the public when the British Chess Magazine included it in its January 1929 issue.

Rules
Despite the larger board, the game plays mostly like the standard game, with the following modifications:


 * Only one of the kings needs to be checkmated to win.
 * Pawns are allowed to move anywhere between one and four spaces on their first move.
 * A pawn may be captured en passant if an enemy pawn can move diagonally to any of the squares it crossed over.
 * A king may only castle with a rook on its side of the board, following the restrictions of the traditional game.

Sub-variants
This chess variant does not not have any notable sub-variants.