Question 1

When did the military start using 24-hour time?

Accepted Answer

The British Royal Navy adopted it in 1915, followed by the British Army in 1918. The US Navy followed in 1920, and the US Army didn't officially adopt it until 1942.

Question 2

Where did the 24-hour clock originally come from?

Accepted Answer

It traces back to ancient Egypt, around 1500 BCE, where astronomers divided the day into 24 equal parts based on star observations at night and a matching division of daylight hours.

Question 3

Why is the 24-hour clock called "military time" in the US specifically?

Accepted Answer

Because the US military was the most visible American institution using the 24-hour format in a country where the 12-hour clock otherwise dominates civilian life. In most other countries, it's simply called "the time," with no special name attached.

Question 4

Is military time the same as the format used in aviation?

Accepted Answer

Yes. ICAO established 24-hour UTC time as the international standard for aviation in 1944, the same format military time uses, just paired with the UTC/Zulu time standard rather than a specific local time zone.

Question 5

When did the 24-hour clock become an international standard?

Accepted Answer

ISO 8601 formally standardized the 24-hour format for international use in 1988, cementing it as the default for computing, aviation, and official documentation worldwide.

History

History of Military Time: From Ancient Egypt to the 24-Hour Clock

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