The castle in Cassiopeia

"A crisis has arisen. In the first book of the series, The Fortress in Horizon, Pretorius and his Dead Enders kidnapped the real General Michkag and substituted a clone who had been raised and trained in the Democracy. But now they find that the clone likes being the most powerful man in the hundred-world Traanskei Coalititon - and having been raised on Earth, he knows how humans think and react. This becomes a many-layered problem for Pretorius and what is left of his Dead Enders. As the only humans on a totally militarized alien world, they must first find where the best-guarded member of the enemy's military - Michkag - is hiding and how many aliens, or regiments, or divisions, are guarding him, and then they must find a way past all his lines of defense to kill or capture him"--