Complex sentence: On 31 July, "Mecklenburg" was replaced by the new dreadnought battleship; "Mecklenburg" was then decommissioned and assigned to the Reserve Division in the North Sea.
Split into simpler sentences: On 31 July, "Mecklenburg" was replaced by the new dreadnought battleship; "Mecklenburg" was then decommissioned. After she was removed from active duty, "Mecklenburg" was assigned to the Reserve Division in the North Sea.