Rare Antique 1941 German Navy U-Boat Captain’s 24H Pocket Watch U-135 Submarine

Historically Significant c. 1941 German Navy Submarine Commander’s 24-Hour Pocket Watch

Offered for your consideration is a remarkable piece of naval history: an authentic, 51mm German submarine captain’s pocket watch, circa 1941. This specific timepiece belonged to Captain Friedrich-Hermann Praetorius, the distinguished commander of the submarine U-135.

Operating deep underwater for extended patrols, submarine crews lived in constant artificial light, completely detached from the natural cycles of the sun. To prevent critical scheduling and operational errors, commanders relied on specialized timepieces. This watch allows the user to instantly verify whether it is day or night without requiring surface observation—a vital tactical tool for the survival of U-135 and its crew.

The 24-Hour Horological Complication

A real 24-hour dial watch only has 24-hour dial notation on the dial. That means that the movement has been expertly altered so that the hour hand doesn’t go 360 degrees around the dial in 12 hours, but rather in 24 hours. The hour hand, for example, pointing to the left would only show 1900 hours, ensuring the captain would know for sure that it was early evening.

Conventional 12-hour watches have a “motion work” involving a 12-to-1 reduction in the gear train from the minute hand. 24-hour watches require a different gearing, featuring a 24-to-1 reduction. To be highly technical, the motion work is the small reduction gear train that turns the timepiece’s hour hand from the minute hand. It is attached to the going train by the friction coupling of the cannon pinion, so the minute and hour hands can be turned independently to set the timepiece. It is located on the outside of the movement’s front plate, just under the dial.

Detailed Condition & Specifications Report

The Dial & Hands The crisp white enamel dial is highly legible and heavily customized for military application.

• Military Insignia: The center of the dial features a prominent Iron Cross motif 

• Vessel Identification: The lower half of the dial is boldly signed “U – 135” above the letters “K.M.” (Kriegsmarine).

• Timekeeping Track: It displays a full 24-hour numeral track with alternating black and red indices for rapid reading, surrounded by an outer 60-minute scale.

• Hands: Fitted with dark spade hands designed for precise alignment against the 24-hour chapter ring.

The Case & Engravings

• Exterior: The substantial 51mm silver-toned case was built with a sturdy bow and crown to endure harsh maritime environments.

• Case Back: The reverse side bears a striking, deep engraving of a submarine profile resting across a cross, bordered by the traditional Gothic script reading “Kaiserliche Marine”.

The Movement

• Engineering: Powering this instrument is a robust manual-wind caliber featuring the necessary 24-to-1 motion work alteration.

• Finishing: The movement features broad, frosted brass plates, exposed winding gears, and an index regulator with an “Avance / Retard” adjustment scale.

• Operating Condition: This historical naval instrument is in perfect working order, winding smoothly and maintaining time accurately.

Item Specifics Summary

• Era: Circa 1941

• Military Context: German Navy / Submarine Fleet (U-135)

• Historical Figure: Captain Friedrich-Hermann Praetorius

• Complication: True 24-Hour Dial (24-to-1 modified gear train)

• Case Diameter: 51mm

• Condition: Excellent Antique Condition / Fully Functional

Terms of Sale

This antique military timepiece is a functioning piece of history and is sold exactly as photographed. Please review all high-resolution images carefully, as they form a definitive part of the description.