Red corner strategy with isolating on a1 and b1

Remember, you want to isolate two white marbles on a1 and b1 if the first marble is placed in the red area. Your strategy is to force your opponent to jump into the a1-d1 line. If the first marble is placed on the a2-e1 line, you first have to force a jump into the d1-g1 line and use the removed g1 to force a jump onto d1.

You leave the board like this:

N = marble of free choice

nn = ring of free choice

First marble placed on a1 or b1:

First marble placed on e1 or f1:

First marble placed on a2 or b2:

First marble placed on b2 or c2:

First marble placed on d2 or e1: