Its probably a couple of different factors, though I'm by no means an expert. 1. Exactly when do you start WW2? 1939 and the invasion of Poland? 1931 and the invasion of Manchuria? Somewhere in the middle? Adding 8 years and a hot war will change the numbers substantially. 2. China was also in the middle of a civil war; how many of those count? 3. The numbers are always squirrelly in wartime, especially civilian deaths in areas where the records were also destroyed. And there have been strong incentives to "adjust" casualty figures for political ends. Stalin and his successors would inflate casualty counts to show that the West were freeloading off of Soviet casualties or blame deaths they caused on the Nazis, China and Japan try to "out-victim" each other wrt to deaths in Nanjing and Hiroshima+Nagasaki, etc.

Provoked only in the "how dare you not sell me the supplies I need to commit more atrocities" meaning of the word.

The really short version is that blue coats indicated regular infantry armed with smoothbore muskets--your classic "let's stand in a couple of lines and shoot until one side gives up"--while the green coats were for skirmishers armed with rifles who acted as a screen, sharpshooters, etc.

It's possible you're thinking of Captain Fluellen from Shakespeare's Henry V who famously wears a leek in his hat during the battle.

Kind of.

The Marine Corps always struggles with how to justify itself as a separate force. The Army does the land fighting and the Navy does the ship fighting and where does that leave the Corps? In other militaries "marines" are just Army soldiers assigned to ships. Plus, you have the issue of it being a component of the Department of the Navy--it's not called the Department of the Navy because the Marines are top dog over there. So, there is a lot of pressure behind the idea of folding the Marines into the Army.

But, the Marines have always found a mission that they will excel at and that requires a different force composition, or mindset, or just particular brand of crazy than the Army--amphibious assault, guarding nuclear weapons on a carrier, or the first reaction force into a conflict zone. They also have done a very good job at building a very strong esprit. You can say that it makes sense from a bureaucratic perspective to do away with the Corps, but from a "winning wars" perspective they keep serving vital functions, so it's not likely they'll ever be disbanded.

https://en.wikipedia.org/wiki/Caravanserai

The Romans used a great deal of steel weaponry and armor. Especially by the time they were regularly interacting with the Egyptians or the Parthians, etc. And there were multiple times entire legions were wiped out. So, your question really doesn't work as it is.

More broadly, steel was adopted in any culture as soon as it was reliably better (both in performance and overall cost) than bronze. And as steel manufacturing materials and techniques increased both the quality and quantity of producable steel, the use of steel increased (e.g. the gladius is a short sword because in part a longer steel sword was more likely to break. The later spatha is approx 6 inches longer in part because the quality of steel improved to the point that a longer, mass-produced sword was reliable enough to issue to the troops. If the earlier legions could have gotten enough reliable spatha-length swords, they'd have used them in a hot second).

The 'secret' of steel was a combination of different raw material supplies with different unknown impurities (which drastically affect the final steel's properties), and the fact that it takes years to train a single smith and lifetimes of trial and error to figure out improvements. They were gauging temperature by color and beating the thing until it felt right...not understanding what's going on in the metal or that carbon infiltration from the fuel is what makes the steel hard or that ore from that mine but not this one has too much phosphorous in it and needs to be refined and forged differently (as I understand it, not a smith myself). There wasn't a secret, just the general advancement of human knowledge before science was really a thing.

It's the difference between a 1920s produce truck and a modern diesel delivery truck. Bigger, more capable, many incremental improvements in all systems, optimized for wartime, but no major obvious changes.

Some of those incremental improvements would be things like double-planking, copper bottoms (arguably not incremental), larger gun decks, bigger guns, framing to reduce hogging, better powder handling, etc. But a ship of the line was recognizably just a later member of the galleon type.

There were many competing measurement systems, at least one per country. Literally look up "pound" in Wikipedia and see the 4 systems used in England. After a while, there were conversions between the most-used systems and rules of thumb a out which system was best for which industry.

Generally, I believe they worked the same way the old standard Kilogram worked--there was one or a small number of reference units--this physical object is exactly one pound/mark/whatever. Standard weight sets were made using simple scales and comparing to the reference unit. And then the weights that merchants would use were made the same way, compared to standard sets (you don't want to handle the reference weight too much). Ideally, any two merchants could pull out a 1-ounce weight and they should balance out in a scale. And they largely did (though dishonest merchants might have a lighter set that just looked like a standard set to cheat people with. The Sheriff might compare weights, too, and then you might have to explain to the man with the keys to your jail cell why yours were so different....)

[ETA: for heavier objects you'd see scales with some mechanical advantage, but of a set amount. A "steel yard balance" is a good example. They were still balances--east to observe, hard to cheat, easy to replicate, as long as the weights were reliable]

Also remember that money was generally a set amount of precious metal. A silver penny contained X amount of silver and should weigh a set amount (ignoring clipping and devaluation). So, a payment could be literally weighed. But, it was still the same simple scales using known weights.

The practice of splitting the kingdom between sons (e.g. Charlemagne's heirs) was intended to prevent conflict because of there being only one heir to the throne. And, in other areas where primigeniture wasn't the rule (Holy Roman Empire, Poland, Ottomans, etc) it just wouldn't happen.

In addition, you did have cases where the ruling king (or queen) set their preferred candidate as heir, which was then ignored after death (the events leading to the Anarchy in England being a good example).

In extreme cases, the ruling king could have disqualified a disfavored heir by forcing them to join a monastery, disinheriting them for some reason, or possibly trumping up a charge against them, but I can't think of an example offhand better than Justinian having Belisarius blinded, which is only barely applicable.