<p>1.d4 + ?</p><p>but 1...cd ep. !</p><p>1.e4 ? threat: 2.Sd7 #</p><p>but 1...fe ep. !</p><p><br /></p><p>1.Rf6 ! threat: 2.Sd7 +</p><p>2...K:d5 3.Rd6 #</p><p>1...c3 2.d4 + !</p><p>2...R:d4 3.Bd6 #</p><p>1...f3 2.e4 ! threat: 3.Sd7 #</p><p>2...R:e4 3.Sf7 #</p><p><br /></p><p>Dresden theme, en passant</p><p>The problem demonstrates the difference between capturing en passant (doesn&#39;t selfblock) and normal capturing (selfblocks).</p>