Intermediate: Capturing a Scout

Illustration of most difficult scenario to capture a scout
Taken from Unladen Swallow's Stratego.com forum post

Sir_richard and I have been analysing scout endgames on gravon. The scout is able to be captured with 4 pieces, in nearly all "normal" gameplay positions. This is the most complex position we found where it was possible to capture the scout with 4 pieces:

This is a difficult position and certainly not easy to force the win here. On each side of the board there is a 6x4 box, which we wager is the minimum squares necessary to capture the scout with perfect play from the scout. Any more room, and the scout will be able to escape.

The scout's goal is to fly between the top and bottom, and the pieces first have to force the scout into one of the two 6x4 boxes before progressing any further.

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As an illustration, a position with no bombs first 3 rows requires a minimum of 5 pieces to capture the scout, as the scout can otherwise alternate between 3 available squares. It is impossible to capture the scout in the below position.

Comment by Napoleon 1er on same topic
In the first pic above you can get him with 3 pieces thanks to bomb placement. The situation with no bomb or flag is impossible in reality. As minimum you will have an extremely vulnerable open flag. In a real situation with a single scout, your flag needs to be sealed. The most difficult conceivable situation is when your flag is sealed in the bottom left corner and your opponents flag is sealed in top right corner. In this situation you need 4 pieces.

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Finally i think you are right with 2x 6x4 open squares you need 4 pieces to capture the scout but with anything less than that you can get it with 3 pieces.