Complex sentence: On 27 October, after approval of the Great Powers, the Greek army re-entered Northern Epirus and the Provisional Government of Northern Epirus formally ceased to exist, declaring that it had accomplished its objectives.
Split into simpler sentences: On 27 October, after approval from the Great Powers, the Greek army re-entered Northern Epirus. The Provisional Government of Northern Epirus formally ceased to exist, declaring that it had accomplished its objectives.