Who wrote the Welsh National Anthem?

Who wrote the Welsh National Anthem?
James James (Iago ap Ieuan, 1833-1902), composed the tune of the national anthem of Wales 'Hen Wlad fy Nhadau' (Land of My Fathers) in 1856. His father, Evan James (Ieuan ap Iago, 1809-93), was a poet and it is believed that he wrote the words. The song was published in the volume 'Gems of Welsh Melody' (1860) and soon became extremely popular. It is not certain when the song was first adopted as the Welsh national anthem.