He competed in distance events, both racewalking and running, at the 1904, 1908 and 1912 Olympics and at the 1906 Intercalated Games.

[4] Bonhag, listed as representing the Greater New York Irish Athletic Association, was named as one of 19 "probable competitors" in the event.

At the 1906 Intercalated Games he placed fourth over 5 miles and sixth over 1500 m. Disappointed and highly motivated to make up for his loss, he entered the 1500 m walk and won the gold medal.

The rules were not clearly set, and many of the nine competitors, including Bonhag, were "skipping" (i.e. changing to half-running).

[5] Two years later Bonhag was part of the American 3 mile team that won the silver medal.