(CBS) — This week is the 40th anniversary of the fall of Saigon. There are over 10,000 Vietnamese who relocated to Chicago in the 1970’s and they’re remembering what’s known as “Black April.”

Dung Nwen was trained by the United States to fight the takeover of Saigon and says its fall was, “The darkest day in our history.”

Nwen spent ten years in a prison camp doing hard labor and was sent to a re-education camp before the United States brought him over as a political refugee.

He now is a job counselor at the Vietnamese Association in Chicago and says the people who made their new home here will always be grateful.

“They come here and they are buying a home, a car and their lives are very stable right now and they feel real happy when they live in new country,” Nwen said.

Nwen says he still hears stories from the so called “boat people” who lost their loved ones trying to escape what was once their homes.