Complex sentence: On their landing at Dover the searchers arrested Cottam and Hart, and the mayor, supposing that Ely was a military man, requested him to convey Cottam to London, and hand him over to Lord Cobham, governor of the Cinque ports.
Split into simpler sentences: On their landing at Dover the searchers arrested Cottam and Hart. The mayor, supposing that Ely was a military man, requested him to convey Cottam to London and hand him over to Lord Cobham, governor of the Cinque ports.