In 1910-12, he also took the Australian and British versions of the World Middleweight Championship, though American boxing historians generally take less note of these titles.

[5] In an important early bout on September 14, 1907, Papke knocked out Terry Martin in the third round at the National Athletic Club in Philadelphia.

[3][9] On March 16, 1908, Papke defeated Hugo Kelly at the Hippodrome in Milwaukee in a ten round points decision that was billed as the world and American 158 pound middleweight championship, though it was not a universally sanctioned bout.

[10] Papke's management successfully used the win as a stepping stone to a world middleweight title match with Stanley Ketchel ten weeks later.

[12][13] Papke won the second fight with Ketchel in an upset at Jeffrie's Arena in Vernon, near Los Angeles, on September 7, 1908, in a convincing twelve round technical knockout, and impressively took the world middleweight title from the reigning champion.

This legend has been dis-proven by boxing historians, as neither the combatants, nor ringside newspaper reporters, corner men, or other eyewitnesses ever attested to or made record of the incident.

[17] A California newspaper, likely using the account of a ringside reporter, inferred the fighting did not commence until after the opening bell, and that both men entered the ring in perfect condition, but that within one minute and twenty seconds, Papke had mounted an attack that determined the outcome of the bout.

[21] In their third meeting, two months later on November 26, 1908, Papke lost his title to Ketchel in an eleventh round knockout in Colma, California, and received a terrific beating in the process.

[23][24] Papke lost the fourth and final meeting by unanimous decision before a large crowd in Colma, California, near San Francisco, on July 5, 1909.

[27] In their heavily attended world welterweight championship bout in Paris, Papke demonstrated superior hitting ability, speed, and defense throughout the match, and was the aggressor through all three rounds.

Papke was defending his World Middleweight title which he took at London's Palladium in a ninth round knockout from Jim Sullivan two months earlier on June 8, 1911.

[5][32] On February 22, 1912, Papke lost to American world middleweight contender Frank Mantell in Sacramento in a twenty round points decision.

[34][35] Papke lost to middle and welterweight contender Leo Houck in the third week of September 1912 at the Olympia Athletic Club in Philadelphia in a six round newspaper decision.

The first two rounds were slow, with Papke staging a comeback in the third which was marred by his tossing Houck around in the clinches and refusing to break at the referee's request.

[36] Papke traveled to Paris where he beat future champion Georges Carpentier in an eighteenth round technical knockout on October 23, 1912.

Though staging a comeback in the fifteenth and sixteenth, Carpentier was floored in the opening of the seventeenth round, when Papke struck him with a left hook, likely taking advantage of the reduced vision on his opponent's right side.

[5] On November 22, 1932, Papke came out of his 1919 boxing retirement to stage a three round exhibition with heavyweight "Fireman" Jim Flynn, the only boxer who ever knocked out Jack Dempsey.

[42] Near the time of his death, he was working as a "host" at Jim Flynn's Cafe in Los Angeles, a beer hall named after the heavyweight boxer.

[6] It occurred at his wife Edna's residence on Balboa Island, part of Newport Beach, south of Los Angeles in Southern California.

[45] He left three sons with whom he lived, Robert, Clifford, and William A. Papke Jr.[46] He is a primary character in the novel, The Killings of Stanley Ketchel, (2005), by James Carlos Blake.