Complex sentence: In 1910 Figgis (with the help of G. K. Chesterton who wrote the introduction to his first book of verse) joined the Dent publishing company, subsequently establishing his own publishing company in which he republished the works of William Carleton and others.
Split into simpler sentences: In 1910 Figgis, with the help of G. K. Chesterton who wrote the introduction to his first book of verse, joined the Dent publishing company. Subsequently he established his own firm in which he republished the works of William Carleton and others.