Tested

Sometimes you must test your opponent's ability to demonstrate what should be elementary skills, especially when time is running short. In the penultimate round of a local tournament a few years ago, the top two players--both experts--were running short of time. The one defending sacked his rook to test his opponent's ability to deliver checkmate with knight and bishop. The gamble worked and they drew. My online opponents often test my ability to deliver checkmate with a queen and king against a lone king in under 15 seconds. I usually pass this test.

This morning, my opponent tested my ability to force checkmate with two bishops in under a minute. I had 59 seconds left when my last pawn was captured and 51 when I finished eliminating his pawns. When checkmate was delivered, 29 seconds remained on my clock. I made 24 moves in 22 seconds to finish the game.

After 69 moves and just over 18 minutes of play in the game 10, we had the following position. My opponent had 53 seconds left to 60 for me.

White to move

70.Nd6 Bxd6

Stockfish would pushed the pawn.

71.Kxd4 Bc5+ 72.Kc4 Bf7+ 73.Kc3 Ka5

I hasten to eliminate White's pawns so that I can begin the mating sequence.

74.Kd3 Kxa4 75.b6 Bxb6 76.Ke4

Black to move

76...Kb4

76...Kb5 leads to mate one move faster.

77.Ke5 Bc4 78.Ke4 Bc5

78...Kc3 is faster

79.Ke5 Kc3 80.Ke4

Black to move

80...Bd4

I teach students to place a protected bishop next to the king because it is easy to see and forces the defending king closer to the edge. 

However, 80...Bd6 leads to checkmate two moves faster, and if White does not move towards the edge, 81.Ke3, then 81...Bd3 is the same sort of move.

81.Kf3 Kd3 82.Kf4 Bd5

Again, there is a move that leads to checkmate two moves faster, 82...Be6

83.Kf5 Ke3 84.Kg4 Be4 85.Kg5 Be5

Time remaining: 0:35 -- 0:42

86.Kg4 Bf4

The recurring pattern that forces the king to the edge.

87.Kh5 Bf5

87...Kf3 is easy to find and two moves faster.

88.Kh4

The rest of my play was perfect and used 12 seconds.

Black to move

88...Kf2 89.Kh5 Kf3 90.Kh4

Those learning how to finish this checkmate should observe the simple way that my bishops drive the king to the corner.

90...Bg6 91.Kh3 Bg5 92.Kh2 Kf2

My king must end up here.

93.Kh3 Bf5+ 94.Kh2 Bf4+ 95.Kh1 Be4#

As is happens, one of my students is finishing the Bishop Award and has this checkmate and two pawn endings remaining.