Complex sentence: However, most of these French client republics were quite short-lived; as the revolutionary republic became the Napoleonic Empire, they were often annexed to France proper or subsumed into more openly French puppet regimes.
Split into simpler sentences: However, most of these French client republics were quite short-lived. As the revolutionary republic became the Napoleonic Empire, they were often annexed to France proper or subsumed into more openly French puppet regimes.