The Marshall Gambit was first introduced by Frank Marshall against Capablanca in 1918. It is a very dangerous option for white unless he is extremely well prepared. One of the many gambit lines against the Ruy Lopez, it has enjoyed great success over the years even at grandmaster level. for example, in the 2004 world championship match between Kramnik and Leko, Leko played this gambit against the world champion and won. White is even trying to avoid this line by playing 8.a4 or 8.h3 instead of 8.c3.
Here is the main line of the marshall along with the start of my game i had with Rad Chmiel where i was white (and won comfortably) as an illustration of an attempted marshall gone wrong. It began with the previously discussed c3 italian and black got an inferior game due to the superior position of whites knight, take a look at the similarities of the 2 positions and then the differences and you will understand what i meant by white avoids such gambits by playing the c3 italian.
So what makes the Marshall so dangerous? Well Black, for 1 pawn gets a large amount of development and alot of pressure against the white king, also black can also, very often be satisfied with just winning material. White is underdeveloped and his king is looking quite unsafe. The practical results are fine for black in this opening. I dont care what the computer would think in a position of this type, i would want to be playing black without a second thought. I have provided you with the Kramnik-Leko game with analysis by Raymond Keene. i have inserted his anaysis lines for you as well. My recomendation, avoid this if your white!
Hope you enjoyed this, If you have anything you want me to look at let me know by leaving me a comment.