New York’s Bravest yesterday kicked off a round-the-clock, 4,600-mile run across the country that will end in the city on Sept. 11 to honor victims of the terrorists attacks.

The firefighters, joined by colleagues from Australia and around the United States, started in Santa Monica, Calif., with an 8:46 a.m. ceremony, commemorating the time the first plane struck.

FDNY firefighter James Dowdell — whose fireman-father, Kevin Dowdell, died on 9/11 — trained by jogging four miles three times a day.

One of the Australian firefighters had a helmet that Kevin had signed for some Down Under firemen visiting New York 12 years ago.

“He recognized my last name and my father’s signature,” said James. “It just shows he’s with us.”

The run raises funds for charity. For info, go to http://www.tourofduty.com.au.