Okay, in Analyze Mode, I first tried 1. Bg2 (so K won't take it). But looking at BK running away through the open top, the power of R to stop that was glaringly obvious. So why not put R up there and leave B alone in his home square?
1. Rf3...Kd1 makes it harder 2. Re3...Kc1 (forced) 3. Re1#
Okay, in Analyze Mode, I first tried 1. Bg2 (so K won't take it). But looking at BK running away through the open top, the power of R to stop that was glaringly obvious. So why not put R up there and leave B alone in his home square?
1. Rf3...Kd1 makes it harder
2. Re3...Kc1 (forced)
3. Re1#