American poet at the center of his generation — descendant of the Boston Lowells (his cousin was the abolitionist James Russell Lowell, his great-granduncle the poet James Russell Lowell), conscientious objector imprisoned in 1943 for refusing the draft after the Allied bombing of civilian targets, four-time hospitalized for the manic episodes that recurred throughout his life, and the figure whose 1959 book Life Studies opened what came to be called the confessional mode in American poetry.
The early work — Lord Weary's Castle (1946), which won the Pulitzer when Lowell was thirty — was densely packed, formally tight, and written from inside the Catholic conversion he had recently undertaken. Life Studies broke that manner open: free verse, plainly autobiographical, drawing on his family, his hospitalizations, his marriage, and his ancestors. The book's effect on younger poets was immediate; Plath, Sexton, and Berryman were all working in or toward the same territory. Lowell's seminar at Boston University in 1958 — Plath and Sexton both attended — became a node in the formation of the postwar American lyric.
The political poems of For the Union Dead (1964), the public refusal of Johnson's invitation to the White House Festival of the Arts (1965) over Vietnam, the appearance with Norman Mailer at the 1967 March on the Pentagon recorded in The Armies of the Night, and the late, contested Notebook sequences (revised into History, For Lizzie and Harriet, and The Dolphin, all 1973) made Lowell a public figure of his moment in a way few American poets have managed. The decision to incorporate his second wife Elizabeth Hardwick's letters into The Dolphin without her permission produced a famous quarrel with Bishop; Bishop's letter on the matter is itself a major document.