Longest mate in King and 2 Queens versus King endgame

Mate in 4

Also available in PGN notation.

White to move
Mate in 4 with Kf2+, Kf4+, Kg3+, Kg4+, Qa1, Qa5+, Qb1, Qb4, Qc1, Qc3, Qd1+, Qd2+, Qe2, Qe3, Qe4+, Qe7, Qe8, Qeg1, Qf2, Qg2, Qg3, Qh2, Qh3, Qh5+, Qh6, Qh7, Qh8, Qhf1, Qhg1 and Qhh4. Worse are Ke2+, Ke3+, Kg2, Qef1 and Qeh4 with mate in 5, and Qe5+ and Qe6+ with mate in 8.
1. Qh7
White mates in 3 after Kc4. Worse are Kc5, Kc6, Kd4 and Kd6 when White mates in 2.
1... Kc4
Mate in 3 with Ke4, Qa5, Qb7, Qc1+, Qc2+, Qc7+, Qd2, Qd7, Qe3, Qe5, Qeh4+, Qf5, Qf7+, Qh5, Qhb1, Qhe4+ and Qhe7. Worse are Ke2, Ke3, Kf2, Kf4, Kg2, Kg3, Kg4, Qa1, Qa7, Qd1, Qe2+, Qe6+, Qe8, Qeb1, Qee4+, Qee7, Qeh1, Qf1+, Qf2, Qg1, Qg3, Qg6, Qg7, Qg8+, Qh2, Qh3, Qh6, Qh8 and Qhh4+ with mate in 4, Qd3+ and Qhh1 with mate in 5, Qc3+ with mate in 7, and Qb4+ with mate in 8.
2. Qc7+
White mates in 2 after Kb3. Worse are Kb5, Kd3, Kd4 and Kd5 when White mates in 1.
2... Kb3
Mate in 2 with Qb1+ and Qcc3+. Worse are Ke2, Ke3, Ke4, Kf2, Kf4, Kg2, Kg3, Kg4, Qa1, Qa7, Qb6+, Qb7+, Qb8+, Qc5, Qc6, Qc8, Qca5, Qcc1, Qce5, Qce7, Qd1+, Qd2, Qd6, Qd7, Qd8, Qe2, Qe3+, Qe4, Qe6+, Qe8, Qea5, Qec1, Qec3+, Qee5, Qee7, Qf1, Qf2, Qf4, Qf7+, Qg1, Qg7, Qh1 and Qh4 with mate in 3, Qcg3, Qeg3, Qh2 and Qh7 with mate in 4, Qb4+ and Qc2+ with mate in 6, and Qc4+ with mate in 8.
3. Qb1+
White mates in 1 after Ka3 and Ka4.
3... Ka4
Mate in 1 with Qa7#. Worse are Ke2, Ke3, Ke4, Kf2, Kf4, Kg2, Kg3, Kg4, Qa2+, Qbb6, Qbb7, Qbb8, Qbc2+, Qc4+, Qc6+, Qc8, Qcb6, Qcb7, Qcb8, Qcc1, Qcc2+, Qch7, Qd6, Qd7+, Qd8, Qe5, Qe7, Qf7, Qg7 and Qh2 with mate in 2, Qa1+, Qbc1, Qbh7, Qd1+, Qd3, Qe1, Qe4+, Qf1, Qf4+, Qf5, Qg1, Qg3, Qg6 and Qh1 with mate in 3, Qa5+ with mate in 5, Qb4+ with mate in 6, Qb3+ and Qb5+ with mate in 7, and Qb2, Qc3 and Qc5 which throw away the win.
4. Qa7#

An endgame analysis by Joe Leslie-Hurd on 16 February 2005.