On 8 February 1917 in London, Fortescue married Margaret Beaumont, a daughter of
Wentworth Beaumont, 1st Viscount Allendale by his wife Lady Alexandrina Vane-Tempest, a daughter of
George Vane-Tempest, 5th Marquess of Londonderry. Peter Fortescue, Viscount Ebrington (1920–1942), only son and
heir apparent, killed in action during
World War II fighting for his father's old regiment the
Royal Scots Greys at the
First Battle of El Alamein. He died unmarried. His mural monument exists in the Fortescue Chapel of St Paul's Church, Filleigh, inscribed as follows: ::"In proud and ever-loving memory of Hugh Peter, Viscount Ebrington, only son of the Fifth Earl and Countess Fortescue, Lieutenant Royal Scots Greys, who was born on 9 December 1920 and killed near El Alamein on 17 July 1942.
He leaves a white unbroken glory, a gathered radiance, a shining peace" •
Lady Margaret Fortescue (13 December 1923 – 25 May 2013), eldest surviving daughter and co-heiress, who married the prominent race-horse breeder
Bernard van Cutsem of
Newmarket, Suffolk, and had issue. Following her inheritance (see below) Lady Margaret found herself frequently commuting the long distance between Newmarket and Devon to administer her estates at Castle Hill and at
Simonsbath on Exmoor. Shortly after 1879 her grandfather
Hugh Fortescue, 4th Earl Fortescue (1854–1932), Master of the
Devon and Somerset Staghounds 1880/81–87, had acquired the reversion of the whole of the former Royal Forest of Exmoor after the death of
Frederick Winn Knight. When Castle Hill was largely destroyed by a fire in 1934, the Fortescue family moved to
Simonsbath House whilst rebuilding was in progress. Lady Margaret devoted much time to attempting to put the Exmoor estate, purchased by her grandfather largely for his sporting interest, onto a profitable footing. The marriage was unsuccessful and eventually the couple were divorced and in 1966 she resumed the surname of Fortescue. In 2001 she gave a lengthy interview for the Exmoor Oral History Archive of the Dulverton and District Civic Society, which provides a valuable insight into many aspects of modern Devon history. • Lady Elizabeth Fortescue (1 October 1926 – 17 January 2010), second daughter and co-heiress, who married William Lloyd Baxendale,
Coldstream Guards, of Uckfield, Sussex, and had issue. ==Death and succession==