War (also known as Battle in the United Kingdom) is a simple card game, typically played by two players using a standard playing card deck
If the two cards played are of equal value, then there is a "war". Both players place the next card from their pile face down and then another card face-up. The owner of the higher face-up card wins the war and adds all the cards on the table to the bottom of their deck. If the face-up cards are again equal then the battle repeats with another set of face-down/up cards. This repeats until one player's face-up card is higher than their opponent's.
War can also be played by multiple people. Each player in a three-player game receives 17 cards, while each person in a four-player game receives 13. Each player must simultaneously reveal their card, just like in the two-player version. If the highest cards played are tied, they will go to war. All players, including those who are not tied, will play one face-down card and the following face-up card. The person who has the highest card at the end of the war obtains all of the cards that have been played. When a player runs out of cards, they are eliminated and are no longer in the game. The game will continue until one player has collected all of the cards. However, the rules often do not specify in which order the cards should be returned to the deck. If they are returned in a non-random order, the decision of putting one card before another after a victory can change the overall outcome of the game. The effects of such decisions are more visible with smaller size decks as it is easier for a player to card count; however, the decisions can still affect gameplay if taken in standard decks.
Variations
Being a widely known game, War has many variations. Recorded variants include:
;Casino War: A simple variation played for money in casinos.
;Three cards: Many play with three cards being played face-down during a war.
;Bettelmann ("Beggar Man") and Tod und Leben ("Life and Death"): German variants mentioned as early as 1833. Uses a 32-card Skat pack for 2 players with cards ranking in the natural order and suits being irrelevant, except that in Tod und Leben, one player plays with the red suits and the other with the black suits. Players get 16 cards each face down. They turn over their top cards at the same time and the higher card wins. If the cards are equal, players turn the next card and the winner takes all four cards. The player with the most cards at the end wins.
;Automatic War: Laying down a two of any suit causes a War to be declared.
;Peace: The opposite of War, in that the lowest card always wins.