Alternatively known as Légal de Kermur or M de Kermur, Sire de Légal, this 18th century Frenchman was the mentor of François Philidor and, arguably, the best chess player in the world during his time.

Biography

Though William Hartston's claim that Légal was the first world chess champion might be a bit hyperbolic, one can certainly make a strong case. After the early, scattered greats such as Ruy Lopez (yes, that Ruy Lopez) and Giaochino Greco were long gone, chess went through a stagnant period before regaining popularity during the Enlightenment, thanks in part to standardized pieces and rules. At this time, Paris was regarded as the chess capital of the world, and by and far the top club to enjoy it in was the newly founded Café de la Régence. The first resident master of this venue? Sire de Légal.

Little is known about Légal, chronologically or physically. He was born in 1702, and first took his seat at the Café in 1730. He was described later in his life as 'a thin, pale, old gentleman...who had sat in the same seat in the Café, and worn the same green coat for a number of years.' He spent the first thirteen of these years establishing his preeminence at the Café, providing running commentary on his victories while taking copious amounts of snuff. But in 1740, he made a move that, although seemingly innocuous, would prove to be the downfall of his great reign. He taught François-Andre Philidor how to play chess.

Philidor had some previous experience with the game (starting from 1736, at the age of ten), but here his studies began in earnest. Anecdotes of the young musician abandoning his pupils to play the old master at a Rook handicap were common, and soon the two interests held equal sway in his life. This divided attention must have been embarrassing to Légal, for Philidor was managing to consistently wallop his teacher at equal odds by 1743. At the Fischerian age of 18, François Philidor had dethroned Sire de Légal as the best chessman of the Café de la Régence.

After his defeat, Légal made one more notable appearance before disappearing into the obscurities of history. One day around the time the two were equally matched, he remarked to Philidor with an amazed tone about stories he had heard of old Italian chessplayers going entire games--without ever looking at the board! Philidor replied confidently that not only was it possible, it was something he did every night in bed, waiting to fall asleep. He soon went on to defeat one, then two players in this style, putting another mark on his rapidly spreading chess reputation.

Légal played Philidor once more in 1754 (a defeat), then likely spent the rest of his life engaged in the same hobby he had enjoyed before. His lost status did not prevent him from living a full life; Sire de Légal died at the ripe age of 90 in 1792.

Légal's Légacies

Aside from his champion status and introduction of Philidor to the world of chess, Légal managed to give two lasting contributions to the game. The first was a game called Sixteen Pawns, often attributed to Légal. The game follows the rules of chess to the letter, with one crucial exception: White's queen is removed and he is given eight extra pawns to be placed in its stead. These pieces can go anywhere on the third or fourth row, in any order, but cannot advance two squares on their first move. This game, also known as 'The Pawns Game', was thoroughly enjoyed by later champions Alexandre Deschapelles and Louis Labourdonnais, who through trial and error found that a swap for only five or six pawns kept the game on its most even level.

The second, much better-known legacy of Légal is a short masterpiece known as Legal's Mate (also Legall's Mate). First sprung against Saint Brie in 1750, the entire mate consists of the following moves (in simplified algebraic notation):

    White	Black
 1. e4		e5
 2. Bc4		d6
 3. Nf3		Bg4
 4. Nc3		g6
 5. Nxe5	Bxd1
 6. Bxf7+	Ke7
 7. Nd5++

I highly suggest that you replay the game's moves on some spare board you have at home. The final position is one of the most clever, elegant mating diagrams I have ever seen.

Sources:
http://dev.jaced.com:8080/htm/c/cbios/cbios_philidor.htm
http://www.chessvariants.com/unequal.dir/16pawns.html
http://misc.traveller.com/chess/history/0-1799.html
Hartston, William. The Guinness Book of Chess Grandmasters. London: Guinness Publishing Ltd. 1996.