Checkmates are divided into two broad categories: simple checkmates and complex checkmates:
1.Simple checkmates are those that are readily observable as inevitable even many moves ahead, and most often occur when few pieces and pawns remain on the board.
2.Complex checkmates are those that are difficult to discern and usually occur when there are many pieces or pawns left on the board.
The reason for this is pattern recognition of the basic pattern or anatomy of mate. [Art of Attack in Chess at page 9 (Introduction)] For checkmate to occur, there must be application of…and usually adherence to…the basic principles and the rules of chess, or deviation there from for sound tactical and strategic purposes, within a plan designed to reach one of three basic groups of squares from which checkmate may occur by attacking (checking) the opposing King on a square within the group from which the opposing King cannot be saved. First, explanation is provided in text followed by a diagram depicting the three basic groups for anatomy of mate patterns.
1.The opposing King must be deprived of eight (8) squares (8 squares to which it may otherwise move; the square it is located upon is called the checkmate square) if it is on a square other than one located in the farthest apart files (the a or h files, also being two of the sides of the chessboard and called the wings), and other than on a square located in the 1st or 8th ranks (being the two other sides of the chessboard, and also usually called respectively each player’s back rank). The nine squares are comprised of the eight squares adjacent to (touching at any point) the square upon which the opposing King is located plus that square as well. The mating pattern or anatomy of a mate in this situation geometrically is a larger square consisting of nine squares – three squares aligned horizontally across three adjacent files by three squares in a column vertically across three adjacent ranks (3 x 3 = 9), with the square upon which the opposing King is located at the center of the larger square/group of nine squares.
2.The opposing King must be deprived of five (5) squares if it is on a square located in one of the four sides of the chessboard other than the four corners of the chessboard (in either the a or h files in any of the ranks 2 through 7, or in ranks 1 or 8 and any of the squares in files b through g). The mating pattern or anatomy of a mate in this situation geometrically is a rectangle consisting of six squares – two squares aligned horizontally across two adjacent files by three squares in a column vertically across three adjacent ranks (2 x 3 = 6), with the square upon which the opposing King is located at the center of the vertically aligned squares on the side of the chessboard.
3.The opposing King must be deprived of three (3) squares if it is on one of the four corner squares on the chessboard (a1, h1, a8, or h8). The mating pattern or anatomy of a mate in this situation geometrically is a medium square consisting of four squares – two squares aligned horizontally across two adjacent files by two squares in a column vertically across two adjacent ranks (2 x 2 = 4), with the square upon which the opposing King is located at the lower left square (a1), or the upper left square (a8), or the lower right square (h1), or the upper right square (h8).
[Art of Attack in Chess at page 9 (Introduction)] These basic anatomy of mate patterns are shown below.
“The final position is called the mating pattern…[which] can be typical (i.e. one which frequently occurs) or atypical. When the combined fighting forces on the chessboard (whether they be the player’s own pieces and/or pawns working together, or in combination using the positioning of other opposing pieces and/or pawns) trap the opposing King in one of the above groups of squares, this is the mating net.” [Art of Attack in Chess at page 10 (Introduction)] There are many different mating patterns that players may use to checkmate an opposing King by creating the mating net…some simple, some complex. These will be covered more fully in other tutorials including the Checking and Checkmate tutorial.