Matt Damon wears a Hamilton Military Ordnance

In August 1941, the Army handed Leslie Groves the job of building the Pentagon, a 63 million dollar project that put thirteen thousand workers on site at its peak. Thirteen months later it offered him the Manhattan Project, and he waited for his promotion to brigadier general to come through on September 23, 1942 before accepting, reasoning that the title of general would carry more weight with academic scientists. A subordinate remembered him as always a driver and never a praiser, but a man with the guts to make difficult, timely decisions. That is the Groves Matt Damon plays in Christopher Nolan's Oppenheimer: the military half of the partnership, opposite Cillian Murphy's physicist.

Hamilton supplied six vintage references for the film, and its page on the production is careful about where they came from: the archives are extensive, the brand notes, but the pieces selected for Oppenheimer were all sourced from collectors, tapped through its network of enthusiasts. Murphy's Oppenheimer wears three civilian models with Art Deco styling. Emily Blunt's Kitty wears a gold Lady Hamilton A-2. Groves gets the military pair: the 1920s Piping Rock, and the watch Hamilton describes as the black service watch on his wrist and lists as the Military Ordnance, a 1940s field piece with a black dial, luminous Arabic numerals, a small seconds register at six, an oversize crown, and a green canvas strap. Oracle Time called it built like a tank, and noted the scale of the whole program: the biggest watch in the movie measures 32 millimeters.

In at least one scene at the desert test site, the watch on Damon's wrist matches neither of the two references confirmed for Groves: it is a small field piece with a pale dial and dark printed numerals, not the black-dialed Ordnance and not the shaped-case Piping Rock. The commitment to real objects ran through the production: Nolan staged the Trinity detonation with real explosives rather than computer graphics, and the picture won seven Academy Awards, including Best Picture. Groves got his third star only at retirement in 1948, an honorary promotion by special Act of Congress, and the Army backdated his date of rank to July 16, 1945, the morning of the Trinity test.