In 1934, he returned to Skye to teach English at Portree High School. After the Spanish Civil War broke out in 1936, he considered volunteering to fight in the International Brigades; according to his daughter, he would have gone if not for family responsibilities. At the time, his mother was seriously ill and his father's business was failing. In January 1938, MacLean accepted a teaching position at Tobermory High School on Mull, where he stayed until December. The year he spent on Mull had a profound effect on him, because Mull was still devastated from nineteenth-century clearances in which many MacLeans had been evicted. MacLean later said, "I believe Mull had much to do with my poetry: its physical beauty, so different from Skye's, with the terrible imprint of the clearances on it, made it almost intolerable for a Gael." He believed that fascism was likely to emerge victorious in Europe, and was further dismayed by the continuing decline of the Gaelic language.