Film footage from 1935 offers a rare glimpse of President Franklin D. Roosevelt walking, in a show of extreme effort that he went to great lengths to hide from the public eye.

Fred Hill of New York was attending the annual Easter Egg Roll at the White House with his family on April 22, 1935, when he used his movie camera to capture the moment Roosevelt emerged from the White House onto the South Portico. In the short, silent film Hill shot that day, Roosevelt, who usually used a wheelchair after being stricken with polio some 14 years earlier, can be seen walking painstakingly along the portico with the assistance of his bodyguard, before stopping at the railing of the balcony to wave to the crowd.

The Franklin D. Roosevelt Presidential Library and Museum in Hyde Park, New York released the black-and-white 16-mm film footage this week after it was donated by Hill’s grandson, Richard Hill of Reno, Nevada. “I’ve kind of jealously guarded this stuff,” Richard Hill told the Washington Post. But now, he said, it “needs to go where it belongs . . . It’s an important part of history that almost got away.”

As a 39-year-old rising politician, Roosevelt first showed symptoms of infantile paralysis, or poliomyelitis, at his family’s beloved Campobello Island retreat in New Brunswick, Canada, in the summer of 1921. At the time, there was no known cure for polio, and it often led to full or partial paralysis. After his diagnosis, Roosevelt withdrew from public life for a time to rehabilitate at his home in Hyde Park, New York, and also traveled to work with physiotherapists at Warm Springs, Georgia. When the resort there was struggling financially, Roosevelt bought the place for $200,000 and turned it into a rehab facility for himself and other polio sufferers.

After Roosevelt resumed his political career, winning the governorship of New York in 1928 and the presidency for the first time in 1932, he took great pains to manage public perception of his disability. Strict White House rules prevented people from taking pictures of or filming him either in his wheelchair or being helped in and out of cars. Roosevelt also worked very hard to develop a way of walking by using heavy leg braces and a cane, and leaning on someone else’s arm—a struggle he also did not want to be preserved on film.

Geoffrey C. Ward, a Roosevelt biographer and trustee of the FDR Museum and Library, writes that before Fred Hill’s newly revealed footage, “only a handful of mostly private snapshots and a few feet of blurry amateur film” have been found to show Roosevelt walking. According to Ward, the Secret Service agents probably didn’t see Hill filming during the Easter Egg Roll because of the unusually large size of the crowd on the White House lawn. (A record 51,391 people entered the White House gates that day.) If they had, they would likely have taken the camera and confiscated the film before giving it back to him.

But the Secret Service didn’t spot Hill—and now we can see the moment he captured for ourselves.