Colle System

The Colle System, also known as the Colle–Koltanowski System, is a chess opening strategy for White introduced in the 1920s by the Belgian master Edgard Colle. It was then further developed by George Koltanowski.
This variation of the Queen's Pawn Game is characterised by a systematic if modest development of White's to support a quick pawn move to the e4-square. The Colle is considered , but inflexible.
History.
Colle and Koltanowski each won many tournaments in the 1920s and 1930s. Colle finished ahead of Tartakower, Euwe, and Rubinstein at various times. The opening had even been referred to as the "dreaded" Colle System. George Koltanowski, in his book "The Colle System", said it offered "solid development", combinations, and a decent endgame, giving White "good chances of not losing against a stronger player". Players like Capablanca and Tal found ways to take the sting out of some of its various lines, however. One such line that has been tested is 3...Bf5, sometimes called the "Anti-Colle".
Plan for White.
Ignoring Black's responses in order to consider White's moves only, the typical plan is as follows:
with White rearranging the move order appropriately. It is a perfectly solid scheme of development, but, inflexibly applied, it cannot offer more than equality against a vigorous Black response. It may be a good tool for avoiding book variations, for Blitz play, or for forcing opponents to think for themselves early on. These days it is considered totally innocuous, and is rarely seen at Master level or above.
The strategic plan behind the Colle System is to aim for a kingside attack. The black king's knight will be either exchanged off on e4, or driven away by the advance e4–e5. This removes a guard from the h7 square, often enabling a classic bishop sacrifice on h7 as the start of a mating attack. Some authors even call this sacrifice "Colle's sacrifice".
Colle–Zukertort System.
One variation of the Colle is the Colle–Zukertort System (named after Johannes Zukertort), characterized by developing the dark-squared bishop on b2. The typical plan is: 1.d4 d5 2.Nf3 e6 3.e3 Nf6 4.Bd3 c5 5.b3 Nc6 6.0-0 Bd6 7.Bb2 0-0, where White, despite their apparently innocuous development, will eventually play for a kingside attack. This system has been frequently employed at grandmaster level by Artur Yusupov.
Games.
A famous Colle System win featuring a slightly unusual Bxh7 sacrifice is Colle–O'Hanlon, 1930. Analysts have debated the theoretical soundness of this sacrifice for many years. 
Black has a variety of approaches to counter the Colle System. One of the most dynamic is to aim for a Queen's Indian Defense setup. White's pawn to e4 slashes at empty space, while Black's pieces are poised to undermine White's centre and attack the . The technique is well-illustrated in the 1929 game between Colle and José Capablanca: 
References.
Bibliography