Complex sentence: The Military Museum of Kalpaki was built in 1975 and includes exhibits-heirlooms of Kalpaki's Battle, which took place during the Italian invasion in Greece (28th October 1940).
Split into simpler sentences: The Military Museum of Kalpaki was built in 1975 and includes exhibits-heirlooms of Kalpaki's Battle. This battle took place during the Italian invasion in Greece (28th October 1940).