On October 26, 1915, he contended for the world welterweight championship against British Jewish boxer Ted "Kid" Lewis, losing in a twelve round points decision at the Arena in Boston.
 Lewis had a clear victory, dominating at both long range and infighting, though Mandot stood up to the punishment and kept several rounds even.
 Lewis scored strongly with his right, dropping Mandot in the first and twelfth rounds.

Mandot fell to the incomparable future world lightweight champion Benny Leonard on December 17, 1915 in a seventh round knockout in New York.
 Never one to shrink from the toughest competition, The York Times wrote that the match, "was a brilliant display of scientific boxing and hard punching for the first six rounds".
 When Mandot rushed in the seventh, Leonard's straight left followed by a right cross to the jaw nearly ended the skillfully fought battle.
Mandot rose to continue and was met with a final onslaught of blows from his challenger.

Before his full retirement from boxing, Mandot considered going into the New Orleans real estate business around 1916 and purchased a few buildings after his retirement.

Mandot defeated Joe Thomas in a tenth round technical knockout in New Orleans on April 30, 1917.
 Mandot had taken a strong lead in every round and Thomas was helpless by the tenth when the referee stopped the bout.

He lost to the less experienced Pal Moran on December 2, 1918 in a fifteen round points decision at the Tulane Arena in New Orleans.
 Mandot was soundly defeated and was down in the fourth round.
 Moran had not fought a professional bout from June of 1917 to June of 1918, and the Times-Picayune of New Orleans, wrote he was "a shadow of his former self", after his loss.
 He had drawn with Moran in a fifteen round points decision on July 15, 1918, at the Tulane Arena in a bout that was billed as a "Southern lightweight championship" and used a three judge system.

In 1918 he became a boxing instructor at Camp Beauregard, a WWI training camp, in Pineville, Louisiana.
On October 26, 1915, he contended for the world welterweight championship against British Jewish boxer Ted "Kid" Lewis, losing in a twelve round points decision at the Arena in Boston.  Lewis had a clear victory, dominating at both long range and infighting, though Mandot stood up to the punishment and kept several rounds even.  Lewis scored strongly with his right, dropping Mandot in the first and twelfth rounds.
Mandot fell to the incomparable future world lightweight champion Benny Leonard on December 17, 1915 in a seventh round knockout in New York.  Never one to shrink from the toughest competition, The York Times wrote that the match, "was a brilliant display of scientific boxing and hard punching for the first six rounds".  When Mandot rushed in the seventh, Leonard's straight left followed by a right cross to the jaw nearly ended the skillfully fought battle. Mandot rose to continue and was met with a final onslaught of blows from his challenger.
Before his full retirement from boxing, Mandot considered going into the New Orleans real estate business around 1916 and purchased a few buildings after his retirement.
Mandot defeated Joe Thomas in a tenth round technical knockout in New Orleans on April 30, 1917.  Mandot had taken a strong lead in every round and Thomas was helpless by the tenth when the referee stopped the bout.
He lost to the less experienced Pal Moran on December 2, 1918 in a fifteen round points decision at the Tulane Arena in New Orleans.  Mandot was soundly defeated and was down in the fourth round.  Moran had not fought a professional bout from June of 1917 to June of 1918, and the Times-Picayune of New Orleans, wrote he was "a shadow of his former self", after his loss.  He had drawn with Moran in a fifteen round points decision on July 15, 1918, at the Tulane Arena in a bout that was billed as a "Southern lightweight championship" and used a three judge system.
In 1918 he became a boxing instructor at Camp Beauregard, a WWI training camp, in Pineville, Louisiana.
Joe Mandot