He agreed to join Jaimihr in opposition to the Rangars.

He agreed to send all his forces to meet Jaimihr's and together kill every Rangar who should show himself inside the city.

And he privately made plans to arrive on the scene too late, and smash Jaimihr's army after it had been reduced in size and efficiency by its battle with Alwa's men.
Jaimihr, unknowingly, fitted his plan into his brother's by determining to get on the scene early enough to have first crack at the treasure.

He meant to get away with that, leave his brother to deal with Alwa's men, circle round, and then attack his brother from the rear.
Finally, he made up his mind once and for all that Rosemary McClean must remain inviolate until he was quite certain that the English had been driven out of India.

He expected that good news within a week.
He was delighted when Joanna, dressed as a man, turned up at his palace-gates and cajoled her way in past the guards.