Complex sentence: After a long career in European politics and diplomacy he was elected as the first head of state of independent Greece (1827--31) and he is considered as the founder of the modern Greek State, and the founder of Greek independence.
Split into simpler sentences: After a long career in European politics and diplomacy he was elected as the first head of state of independent Greece (1827--31). He is considered as the founder of the modern Greek state, and of Greek independence.