In 1941 Marathon delivered its first military order and went on to supply field watches to Allied forces through the Second World War. The black GPM, reference WW194003BK-0108, carries that lineage forward as a 34mm automatic field watch on a DefStan nylon strap, with a clean dial that bears no government markings.

The General Purpose Mechanical is made to MIL-PRF-46374G, Type II, Class 4, the modern descendant of the 1960s GG-W-113 specification, and it keeps the elements that made those early watches useful: a high-contrast black dial, 12- and 24-hour scales, and a crown that is simple to operate. Marathon updates the formula with sapphire crystal and tritium tubes that glow continuously for years. The black composite fibreshell case is light enough that you forget it is there.

What sets this listing apart is the strap. The DefStan nylon is the British-pattern military style, and at 11 inches it has extra length to go over a jacket cuff or fit larger wrists comfortably. Under the dial, a 24-jewel automatic movement (NH35-based) winds with wrist motion or by hand and stores roughly 41 hours of reserve.

Key Specs: Marathon GPM Black NGM DefStan

• Reference WW194003BK-0108
• 34mm composite fibreshell case in black; 12.5mm thick; 41mm lug to lug
• Automatic movement with hand-wind function, 24 jewels, about 41 hours reserve
• 3 ATM water resistance
• Sapphire crystal, pressure crown
• Tritium tubes on hands and hour markers
• Matte black NGM dial (MARATHON only)
• Black DefStan nylon strap, 11", 16mm lug width

Eight decades of field-watch know-how, condensed into 34 millimeters.