The Lawnmower Mate is an easy checkmate typically performed by a queen and rook (or just two rooks). The two pieces work together to push the enemy king to the side of the board. Since it is a very common checkmate pattern, it is one of the first checkmate methods that a beginner should learn.
The examples below will focus on how to perform this checkmate with two rooks. (One or both of the rooks could also be a queen, which will often make the checkmate even easier.)
Lawnmower Mate Example
Diagram above: 1.Rb7+ will force the black king to move to the last rank, onto the side of the board. Note the important role of the rook on a6, which prevents the black king from escaping towards the middle of the board.
Black’s king is forced to move to the side of the board. 1… Ke8 or Kf8 or Kg8. They all lead to the same outcome:
Diagram above: 2.Ra8# completes the Lawnmower Mate. Again, note now the important role of the rook on b7–the black king can’t return to the 7th rank. Beginners often make a mistake and check with the wrong rook, allowing the king to escape.
Diagram above: Giving check with the wrong rook will allow the black king to escape to the 7th rank. This is an inconvenience for white and they will have to return the rook to the 7th rank.
Interesting Notes on the Lawnmower Mate
The diagram below is my attempt to demonstrate where the checkmate method got its name:
Diagram above: The Lawnmower Mate is named after the alternating advance of the 2 rooks that resemble the visible lines on a freshly cut lawn, pushing the enemy king all the way to the edge of the board. It is because of this “rolling” action that the pattern is sometimes referred to as the Rook Roller’s Mate.
If your opponent is stubborn, and their king is already close to the rooks, they may try to undermine your attempts by attacking a rook with their king:
Diagram above: 1… Kc8. Black moves the king close to the rook, threatening to capture the rook on c7. This will delay white’s plans a little.
I’ll show you a useful technique to use in this situation:
Diagram above: 1.Ra7 is a neat little move that defends the other rook on b7 and also places the black king in zugzwang. Black’s only legal move is 1… Kd8, forced to move away from the rooks, after which white can play Ra8# (or Rb8#).