The Last Charge. Mechwarrior: Dark Age #29

Anson Marik is at his wit's end. The Lyrans are pressing on his borders, his chief tactician has resigned, and his abilities as a leader are failing him. Now his enemies are on the move, taking the Commonwealth planet by planet, forcing Marik to pull his forces back in a bravely-fought running retreat. And if Marik cannot gather his strength to stop the invasion, his people will be doomed...