Ken Burns says PBS’ new 18-hour documentary film series The Vietnam War is “without a doubt” the most ambitious project he and his partners ever have undertaken. This may come as a surprise to fans of the Civil War docuseries chronicling the deadliest war in American military history, that made Burns a household name and got him declared, by more than one pundit, the most accomplished documentary maker of his generation.

Even PBS, in today’s trailer release, noted The Vietnam War, which it will debut in fall 2017, rounds out a trilogy of Florentine Films’ exploration of American wars that began with Burns’ “landmark series” The Civil War (1990), followed by Burns’ and Lynn Novick’s seven-part series about World War II, The War (2007).

This new project, from Burns and Novick, was six years in the making.

“There was no way we could avoid telling this story,” Burns emotes in the trailer which, hopefully, he will explain fully at TCA in January.

In today’s trailer release, Burns is quoted as saying “The Vietnam War was a decade of agony that took the lives of more than 58,000 Americans,” and that “Not since the Civil War have we as a country been so torn apart” – though maybe that quote was written before the presidential election.