Between 1891 and the Second World War, the population in Welsh-speaking areas became increasingly bilingual although the Welsh language remained the customary language of a large majority.
Rhwng 1891 a’r Ail Ryfel Byd, daeth y boblogaeth mewn ardaloedd Cymraeg yn gynyddol ddwyieithog er i’r Gymraeg aros yn iaith arferedig mwyafrif mawr.