Chess is a game. It has been used to train fighting men. “Chess involves a struggle of will, and it contains what has been termed the essentials of fighting – to strike, to move and to protect.” (Jan Kuylenstierna – Swedish National Defense College)
The game is strictly computation and logic. Any randomness and chance is strictly the reaction of the opponent and his moves. The only way to win the game is to get the opposing king in check in such a way that he cannot get out of it. Pieces that strike always take the opponent’s piece: there is no “outcome uncertainty.” It is an abstraction of war.
By putting into the game that there is only a probability of positive outcome, the risk of taking the square is not just that the opponent might retake the square next turn, but that the square might be lost in the attempt right now. Thus fighting for the square makes the game of chess that much less abstract.
Traditionally the chess board has 64 “fields” that make up the 8 rows and columns. A single troop fills a field and only a single troop can take an enemy field by killing their troops. There is no deterioration of strength or moral in the troops fight after fight. They are fresh each turn.
This set field of 8 by 8 fields is the battlespace the player works with. Your pieces can become blocked by your own troops. The only seeming way to change the space was to add or remove squares or change the shape of the board. Some chess variants do this. However, another way to open up the battlespace is by allowing additional troops onto the field (square). The simple expediency of co-occupation of squares creates more fluidity to the war.
Traditionally chess pieces have been used in combination to capture and check. With co-occupation of squares, one truly can experience combined arms with the possibility of sending re-enforcements into a combat field.
The “core-game” of the Fantasy Chess chess variant allows one to have a less abstract feel for the warfare going on. With more play experience, the “deep planning” that occurs in traditional chess will start to occur here, allowing you to move from just a tactical fight to a strategic battle.
And the fact that you can declare all your surviving pieces “veterans”, you can go from the strategic of a single chess game into a strategic of a series of games in a campaign.