Wrestling at 165 pounds (75 kg), Robertson won an individual Big Six Conference championship and earned All-American honors in 1935.

He suffered a knee injury in 1936 and chipped a vertebra in his neck during tryouts for the 1936 Summer Olympics in Berlin, but returned in 1937 to win a second Big Six conference title.

He participated in the invasion of Normandy at Omaha Beach in 1944; during the battle an artillery shell exploded nearby, resulting in injuries that included permanent loss of much of his hearing.

Fifteen of his wrestlers won individual NCAA titles, including three-time champion Dan Hodge and Olympians Dick Delgado and Bill Borders.

[1] Terry McCann, two-time NCAA champion from the University of Iowa, credited Robertson for him making the Olympic team that year.

During a hot August workout prior to tryouts at the Olympic training camp in Norman, Oklahoma, McCann fainted and was treated at the infirmary for heat exhaustion.

After deciding he would not be able to recover in time, McCann drove home to Tulsa, but Robertson insisted he return to Norman and compete.

McCann arrived back in camp the following day to win two consecutive matches and earn his place on the Olympic team.

[1][6] On February 12, 2000, the University of Oklahoma dedicated the Port Robertson Wrestling Center in honor of service to the school.