One Watch, I Ruled Two Worlds

Leonard, of rural origins, loses his job and is evicted. After obtaining a time-travel watch, he shuttles between modern and ancient times.

Using modern supplies and knowledge, he resolves a national reparation crisis for H Country, repels Northern Qi's aggression, challenges the Prime Minister, wins the princess's admiration, becomes involved with the empress, and ultimately helps her seize power while taking revenge on his enemies in the modern era.