Who invented military time?
The beginning of 24 hour time periods is rooted in early Egyptian culture. Other time keeping systems were in use prior to this period, and continued to be used in the rest of the world for a considerable amount of time after the end of the old Egyptian civilization. However, it was the Egyptians who were the first to use the 24 hour clock. Their system evolved around the time it took certain constellations to pass through the sky, eventually giving rise to a 360 day year.
However, in the early days the 24 hour clock made use of what are called temporal hours. Temporal hours reflect the differing amounts of daylight present during different seasons. To account for this so that day and night had equal hours, the actual length of time that the unit “hour” lasted for was altered. The system was sufficient for measuring seasonal shifts, and events that took place over long periods of time; but its usefulness was limited for measuring celestial events that occur every day. The astronomer Hipparchus, between 147 and 127 BCE, developed the idea of equinoctial hours. These were hours that were equal in length regardless of the season. The length of the hour, 60 minutes, was determined during the equinox, when the periods of day and night are equal. For a long time after the equinoctial hour was created, laypersons continued to use temporal hours in their everyday lives. However, the advent of the equinoctial hour was critical to the advancement of astronomy elsewhere.