Complex sentence: Croker, who is known for his extensive research into ancient Irish poetry and Irish folklore, attended his wedding and then helped Ryan with contacts and accommodation when Ryan lived in Croker's hometown of Cork in 1822 and 1823.
Split into simpler sentences: Croker, who is known for his extensive research into ancient Irish poetry and Irish folklore. Croker helped Ryan with contacts and accommodation when Ryan lived in Croker's hometown of Cork in 1822 and 1823.