Explanation

This checkmate pattern is named after Samuel Boden. The game Schulder - Boden, London 1853 reached the following position:

The game continued 13...d5! 14.Bxd5 Qxc3+!! 15.bxc3 Ba3#.

Examples

White can deliver Boden's mate with Bxg6#.
The bishop b6 on the criss-crossing diagonal b6-d8 guards the escape square d8.

Boden's mate can also happen in the middle of the board as in the following example:

Black can deliver Boden's mate with Qg2#.
The bishop h6 on the criss-crossing diagonal h6-c1 guards the escape squares f4 and e3.
The pawns on f6 and c5 are helping by guarding the escape squares e5 and d4.
One of the bishops can be replaced with a queen (here on g2), and the pattern remains the same.

Pattern matching

As in the famous game, Bodens mate can often be achieved against a king that has castled long, with a bishop (or a queen) controlling the diagonal including the escape squares c7 and b8 (or c2 and b1).

Related patterns

In double bishop mate, two bishops checkmate the king on parallel diagonals.
In Balestra mate, a bishop gives mate, with support from a queen.