 On 29 August 1831, he married firstly Harriet Georgiana Cosby, youngest daughter of Thomas Cosby, of Stradbally Hall and his wife Charlotte Elizabeth Kelly, and had by her two daughters and three sons.She died in 1845 and Trench married secondly Elizabeth Oliver Gascoigne, second daughter of Richard Oliver Gascoigne, of Parlington Hall and his wife Mary Turner, in Aberford on 10 February 1852.He lived much of the year at Castle Oliver, which was built in 1845 by his second wife and her sister Isabella.