This is an easy google search.

But briefly, a nautical mile is based on the size of the earth. It honestly makes way more sense than a statue mile, which is just some random thing.

A knot log was a method of tying knots evenly spaced into a rope and then tossing the rope over the side with a piece of wood at the end. Wait a minute, stop the rope, see how many knots had gone out when you pulled the rope back up. So speed became abbreviated as knots, which is now nautical miles (vs statue miles, which are shorter) per hour.

A quick trip to Google reminded me that a fathom was just the distance between a sailor's outstretched arms, useful when hauling up an anchor.

We gave up on fathom for the most part, but the others are still useful.

The various kingdoms of the world all had different units for measurements, and when you're trying to communicate between different cultures, the first thing you need is standard meanings of terms. So the merchants and navies of the world standardized the nautical mile, for example.

And yes, nautical miles per hour (knots) is still a commonly used measurement of speed, even if things like "fathoms" and "leagues" have fallen into disuse.

IIRC, most of the "Imperial" units (I'm from a metric country lol) were based on ancient Roman units. Back then, a mile was the distance traveled by a soldier in one hour. Man those guys were fit.

I walk 2.5 miles per hour and I'm not a Roman imperial soldier.

Yeah, but you are not carrying the kit of a soldier, which includes full armour, weapons, and provisions. Nor maintaining that speed for an average of ten hours a day and often more. Nor doing this all in conjunction with other men, and while remaining alert and ready for combat.

Strategic movement speeds are much slower than what you think because you have to factor in everything.

Yeah but you're doing that unencumbered, with modern shoes and on paved roads.

In all fairness, this does assume decent footwear and a Roman paved road, with worse conditions being expected to slow units down.

But a lot of encumbrance plus having to do it for a long time makes it a lot more impressive. At the time, it was quite the feat mostly because the Romans had the infrastructure make it happen.

When I go hiking I am encumbered and definitely not on paved roads. Guilty of modern shoes. Still way over 1 mph on all but the steepest trails.

No, but I did take years of Latin where we studied this stuff, and I also know my way around hiking.

But then again, google can tell me that the Roman imperial soldiers were 3x as fast as you give them credit for.

A nautical mile is equal to 1/60 of a degree of latitude (or one second of latitude) on the earth.

I don’t think it’s so much that they “came up with their own,” it’s more that boats are the world’s oldest form of transportation…Lol

I still uae fathoms when im Hunting deep sea giant squid

That is also why we all pretty much use Arabic Numerals. Ever tried to do math with Roman Numerals?

The paragraph after the one you highlighted says that the 3mile/hour number is generous and based off some battle where exceptional marching speed could have been expected.

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