<human>: Hunter was born in New York City, the son of Gertrude (nee Gelien) and Charles Kelm. His mother, from Hamburg, was a German Roman Catholic immigrant, and his father was Jewish. Hunter's father was reportedly abusive, and within a few years of his birth, his parents divorced. Tab grew up in California with his mother, older brother Walter, and maternal grandparents, John Henry and Ida (nee Sonnenfleth)

One of Hunter's first films for Warners was The Sea Chase (1955), supporting John Wayne and Lana Turner. It was a big hit, but Hunter's part was relatively small. Rushes were seen by William Wellman, who cast Hunter to play the younger brother of Robert Mitchum in Track of the Cat (1955). It was a solid hit and Hunter began to get more notice.  His breakthrough role came when he was cast as the young Marine Danny in 1955's World War II drama Battle Cry. His character has an affair with an older woman, but ends up marrying the girl next door. It was based on a bestseller by Leon Uris and became Warner Bros largest grossing film of that year, cementing Hunter's position as one of Hollywood's top young romantic leads.  In September 1955 the tabloid magazine Confidential reported Hunter's 1950 arrest for disorderly conduct. The innuendo-laced article, and a second one focusing on Rory Calhoun's prison record, were the result of a deal Henry Willson had brokered with the scandal rag in exchange for not revealing his more prominent client Rock Hudson's sexual orientation to the public.  Not only did this have no negative effect on Hunter's career, a few months later he was named Most Promising New Personality in a nationwide poll sponsored by the Council of Motion Picture Organizations. In 1956, he received 62,000 Valentines. Hunter, James Dean and Natalie Wood were the last of the actors placed under exclusive studio contract to Warner Bros. Warners decided to promote him to star status, teaming him with Natalie Wood in two back-to-back films, a Western, The Burning Hills (1956), directed by Heisler, and The Girl He Left Behind (1956), a service comedy. These films also proved to be hits with audiences and Warners planned a third teaming of Hunter and Wood. Hunter rejected the third picture, thus ending Warner's attempt to make Tab and Natalie the William Powell and Myrna Loy of the 1950s. Hunter was Warner Bros.' most popular male star from 1955-1959. CANNOTANSWER

Using a quote from the above article, answer the following question: How was that a breakthrough role
<bot>: It was based on a bestseller by Leon Uris and became Warner Bros largest grossing film of that year,