Complex sentence: But the execution of Guru Arjan at the hands of Jahangir and imprisonment of Guru Hargobind definitely showed that sterner days were ahead, and the policy of mere peaceful organisation no longer sufficed.
Split into simpler sentences: But the execution of Guru Arjan at the hands of Jahangir and imprisonment of Guru Hargobind definitely showed that sterner days were ahead. The policy of mere peaceful organisation no longer sufficed.