PASADENA, Calif. (AP) – PBS essentially has given a lifetime contract to documentarian Ken Burns, whose upcoming 14-hour series on World War II was described by network chief Paula Kerger Saturday as his greatest work.

Burns, essentially the nation’s highest-profile documentarian since his series “The Civil War” created a sensation, has agreed to air his work exclusively on PBS until 2022, the network said. Burns is 53 now.

“What it represents is an extra commitment from Ken that he’s planning to spend the rest of his professional life working with public television,” Kerger said.

Burns has projects in the works about the National Parks system and Prohibition, she said.

His film “The War” is “going to be one of those seminal events, not just in public broadcasting history, but in broadcast history,” she said.

The series follows four American towns – Waterbury, Conn., Mobile, Ala., Sacramento, Calif., and Luverne, Minn. – through the war years, focusing both on the soldiers from the towns sent to war and the families and friends left behind.

Burns was reluctant to take on another war, particularly since he’s so identified with “The Civil War” project. But he realized it was important to capture the memories of the people who fought World War II before they die, and that many students today don’t understand what happened, she said.

Kerger said PBS is hoping for clearer direction from the FCC about language issues, since some obscenities are used by former soldiers interviewed by Burns to describe their experiences.

She said she’s committed to airing the documentary as Burns has made it. The fact that a handful of swear words in the documentary are an issue is an example of an unintended consequence of the government’s crackdown on the coarsening of TV, she said.

It’s possible, however, that an edited version of the documentary will be sent to PBS stations not wishing to risk an FCC fine, she said.

“The War” is set to begin on Sept. 17. PBS will air it in different fashions, both once a week and daily, in order to give it greater exposure.

Still, Kerger faced heat from television critics at a meeting Saturday for scheduling it on the same week that broadcast networks will be debuting their fall series. Some critics wondered whether PBS wasn’t unnecessarily reducing the amount of attention the series will get.

John Boland, PBS chief content officer, said PBS didn’t want to “go into hibernation” just because the commercial networks were starting a new season.