Complex sentence: The regiment embarked for Corfu in 1853 and then landed in the Crimea for service in the Crimean War: it saw action at the Siege of Sevastopol in winter 1854.
Split into simpler sentences: The regiment embarked for Corfu in 1853 and then landed in the Crimea for service in the Crimean War. It saw action at the Siege of Sevastopol in winter 1854.