Complex sentence: John Thomas McManus (1904--November 1961) was an American journalist active in progressive politics in the 1950s and 1960s best known as co-founder of the "National Guardian", a left-leaning newspaper.
Split into simpler sentences: John Thomas McManus (1904--November 1961) was an American journalist and well-known name in progressive politics in the 1950s and 1960s. He cofounded the "National Guardian", a left-leaning newspaper.