Flank Opening (Ware Opening)

1. a4?! is an unorthodox opening. It does not help White to develop their pieces or stake a claim to the centre. It is almost like White has passed their first turn: functionally, they are playing a tempo down.

It is most common with beginners who think that their rooks are powerful pieces, and wouldn't it be good to develop them first? Unfortunately, rook lifting (a4, Ra3, Rd3 etc) is too slow and gives Black plenty of time to develop all their minor pieces. Rooks come alive later in the game, when files begin to open.

After 1. a4, Black gets to decide which pawn to put in the centre. 1...e5 is the main line (as much as there is a "main line"), taking space and opening the a3-f8 diagonal for Black's bishop. As long as White responds with something like 2. e4 then they do not fall too far behind and the game is even. A classic beginner blunder (called sometimes the meadow hay trap) marries the plan of an early rook lift with a lack of board vision: 2. Ra3?? Bxa3.

1...d5 is also very sound.

1...a5?!, which might be called the "symmetrical variation", at worst fails to capitalise on White's irregular play.

1. a4 is named for Preston Ware who played it in 1880 during the 5th American Chess Congress.^[1][2] With the black pieces he played 1...a5.^[3] Contemporaries of Ware called 1. a4 the meadow hay opening.^[4]

Magnus Carlsen played it against Teimour Radjabov in the 2012 World Blitz Championship, apparently as an in-joke referencing Radjabov's comment, "Everyone is getting tired. You might as well start with 1. a4 and you can still beat them."^[5][6]

In May 2024, the opening gained notoriety after Grandmaster Brandon Jacobson, under the pseudonym Viih_Sou, won a sixty-nine game blitz match against Daniel Naroditsky by playing 1. a4 and 2. Ra3? with White and 1...a5 & 2...Ra6? with Black every game, voluntarily sacrificing the exchange. Chess.com banned Viih_Sou for fair play violations and the line became known as the "banned gambit" or "Viih_Sou gambit". Jacobson took to Reddit to reveal their identity and deny allegations of cheating.^[7][8]

Brandon Jacobson went on to win with 1. a4 (though not 2. Ra3?) against Hikaru Nakamura in the 2024 World Rapid Championship.^[9]

Wikipedia has related information at Ware Opening.