user13147: From Fine's BCE:

I can only see the pawn getting to a2 after 1.d6+ Kd8 2.e6 a4 3.Kf6 a3 4.e7+ Ke8 5.Ke6 a2 6.d7#. That's three pawn moves, not four.
What is the more resistant defence I missed?

user14202: 1.d6+ Ke8
2.e6 a4 (pawn move 1)
3.Kf6 a3 (pawn move 2) [Note: 3.e7 Kf7!]
4.e7 a2 (pawn move 3)
5.Ke6 a1=Q (pawn move 4)
6.d7 mate

13147: <p>From Fine's BCE:</p>

<p><img src="https://i.stack.imgur.com/kL6dq.jpg" alt="enter image description here"></p>

<p>I can only see the pawn getting to a2 after 1.d6+ Kd8 2.e6 a4 3.Kf6 a3 4.e7+ Ke8 5.Ke6 a2 6.d7#. That's three pawn moves, not four.</p>

<p>What is the more resistant defence I missed?</p>
 14202: <p>1.d6+ Ke8</p>

<p>2.e6 a4 (pawn move 1)</p>

<p>3.Kf6 a3 (pawn move 2) [Note: 3.e7 Kf7!]</p>

<p>4.e7 a2 (pawn move 3)</p>

<p>5.Ke6 a1=Q (pawn move 4)</p>

<p>6.d7 mate</p>
