1.Ra7
Confining the Black King to the back rank. Why?
1...Kd8 Heading towards
the rook. Rooks are vulnerable from attack from the diagonal.
2.Kd2
Kc8
3.Kd3
Kb8
4.Rh7 Running as for away
as possible. The Black King will have to take a long walk to catch up again!
[If 4.Kd4
Kxa7 Game is drawn due to
insufficient material]
4...Kc8
5.Kd4
Kd8
6.Kd5
Ke8
7.Kd6
Kf8 [If
7...Kd8
8.Rh8# Checkmate!]
8.Ke6
Kg8 Attacking the rook
again!
9.Ra7
Kf8
10.Rb7 A very important
waiting move! Why? [If
10.Kf6 Ke8 running away
and increasing the number of moves.]
10...Kg8
11.Kf6
Kh8
12.Kg6 Now the Black
king must turn back!
12...Kg8
13.Rb8# Checkmate! The
White King covers the three squares in front and the Rook covers the back rank.
As it is the back rank three squares are short. If the Black King is in the
middle of the board, he could have got some more options for moving! 1-0