Complex sentence: By February 1864, Admiral Bonard had accumulated sufficient reinforcements to attack and seize Dinh's main strongholds in the Tan Hoa and Go Cong areas, inflicting heavy casualties on the partisans and forcing them to retreat in disarray.
Split into simpler sentences: By February 1864, Admiral Bonard had accumulated sufficient reinforcements to attack and seize Dinh's main strongholds in the Tan Hoa and Go Cong areas. He inflicted heavy casualties on the partisans and forced them to retreat in disarray.