His early poetry was in English, but soon came to the conclusion that his true love was for verse in Gaelic, and certainly by the mid 1930s he was well known as a writer in this tongue.
Much of his work was specifically political, and his position was Marxist, although he was also a skilled and delicate writer of love poetry. During World War II he served in North Africa, and was wounded on three occasions, one of which was severe.
His work in the field of Gaelic poetry at the time which very few writers of substance were working in Gaelic at all, has led to him being seen as the father of the Gaelic renaissance. His poetry articulated in Gaelic the crimes of the 20th century and modernised and reinvigorated the language in the process, drawing clear and articulate analogies between such tragedies as the Highland Clearances and the contemporary viciousness and injustice of events in places such as Biafra and Rwanda.
The poem Hallaig is one of the lyrics included in Peter Maxwell-Davies' opera The Jacobite Rising.