But in modern day with big jets, fast transports, such stance of not having army big enough seems not wise.

Let's start with the revolutionary wars. About 200,000 Americans picked up arms during the revolutionary war, which is a lot! Especially next to the 121,000 troops the British had in 1781.

Except that 200,000 is wartime total, while the 121,000 figure is all at once in 1781. The average number of men under arms that the Americans had was about 40,000, roughly on par with the 48,000 committed by the British in the colonies. Keep in mind that this was a demobilized and underfunded British army, with the British coffers being empty after the 7 years war.

There are a series of battles on the continent that would see more men committed to a single battle than the Americans had under arms at once during the revolutionary wars. The Prussians (Germans to you and I) committed 20,000 to the Battle of Mollwitz in 1741, and 36,000 to the Battle of Hochkirch in 1758. The Austrians committed 80,000 to that exact same battle, twice the number of Americans under arms twenty years later.

By 1776 Frederick the Great would have 187,000 men under arms during the peace.

There is a very good reason why the founding fathers wanted to remain aloof from continental interests.

The US Civil War is the bloodiest war that we've participated in, because every casualty was by necessity an American. It was a much larger conflict compared to the revolutionary war, but it doesn't really stand out as conflict containing large armies, compared to other European conflicts before and after.

2,200,000 Americans fought on the Union and 750,000-1,000,000 Americans fought for the Confederacy during the war. The estimated peak size of each army was 700,000 for the north, and 360,000 for the south. So we're an order of magnitude up from the revolutionary era, how does this compare to other wars on the continent?

.... Not good, as it turns out. The French revolutionary government managed to get a peak of 800,000 men under arms during their various wars half a century earlier. The Napoleonic wars saw 1,200,000 men under arms on the French side at once, with roughly 1,450,000 British, Prussian, and British soldiers arrayed against them. Napoleon dragged 685,000 men into Russia (and left half of them there...). To put that into perspective, he dragged the entire Union army into Russia, and then left the entire Confederate army dead on the outskirts of Moscow, then he kept fightinng.

Heck, even previous conflicts dwarf the civil war. The 30 years war (1618-1648) saw armies of roughly half a million squaring off for 30 years.

The Franko-Prussian war (1870-1871) saw a max of 950,000 Germans (we can call them that now) squaring off against 710,000 Frenchmen at once.

Side note: the one thing the Civil War has going for it is that it previewed the horrors of WW1 much better than the napoleonic wars did, even if it was smaller. Better artillery and better rifles started showing up by this time, including limited numbers of repeating rifles. Apparently the European powers sent observers to see how this would all work out, and if that's true then holy crap did they not learn the right lessons.

And between these large conflicts you find .... nothing. From 1800 to 1810 the US had less than 10,000 men under arms total (excluding reserves). You see a nice little spike of 20,000 or so around the war of 1812, having your capital burned will do that to you, but it's all kind of cute compared to the millions of men under arms trying to kill each other in Europe at that exact time. The numbers remain in the 20-40k range until the Civil War, and then it climbs into the heady territory of .... 50,000 men and slowly climbing. At the start of WWI the US had 130,000 men under arms, less than half the number of casualties that the French would suffer in the first month. The first battles of WWI would show the French and Germans committing twice as many men to a single battle each as the US had available in total.

Of course, we know how this ends. The US eventually builds up its army and comes in to finish off an exhausted Germany. Then we start keeping larger and larger armies until today, when we outspend the next 7 countries combined. Nowadays we absolutely do keep a very large army, but from the very beginning? Not so much.

I am just going to leave this here because somehow it got lost along the way:

- US population 1776: 2.5m (Revolutionary war)

- US population 1861: 31.4m (Civil war)

- US population 1914: 99.1m (WW1)

- Europe population ~1776: 200m

- Europe population ~1861: 280m

- Europe population ~1914: 482m

You are comparing apples to oranges all over the place.

200,000 out of 2,500,000 is 8%. If 8% was enlisted in the regular US army in 2018 (population: 328m) that would give you an army of 26 million people. To put things in perspective: the largest army in the world, with human population at its historic maximum, has 2.1 million people (China, with a population of over a 1.3b people).

Part of what makes massive countries so dangerous is that they can field huge armies without damaging their economic base, which is why you’ll never see China field an army with 5% of their population, while smaller countries might have to.

This means by your measure the largest armies in the world are fielded by small tribes, which might have over 50% of their population at arms! Except this is absolutely silly, and we all know it.

But fine. Let’s play that game.How big are America’s armies by percentage of population?

You can’t use total people served, because that’s not the size of the army. When you measure total served you’re picking up the size of the army, the length of the war, and various bits about how recruitment and retention worked. The actual size of the army was 40,000 in 1776, which is a more prosaic 1.6% of the population.

By that measure the revolutionary army is decently sized (1.6%), the civil war army is actually about the same size (3.2%, or 1.6% per belligerent).

In between the wars you effectively have no army, by percentage. With 20,000 men under arms before the Civil War that’s 0.06% of the population. The army we had on the declaration of WW1 was a little bit larger at 0.16%.

Contrast that to Prussia above which had 187,000 men under arms in 1776 and had a population of 9.7m in 1800, which yields over 2.0% at peace, and that’s fudging the numbers in your direction because I can’t find population totals for 1776, which would be quite a bit lower.

France has a population of about 30m during the napoleonic wars, and they pushed a peak of 1.2m Frenchmen into the field at once, which was 4% of their population.

I could go on, but I think I’ve made my point. When other countries are tossing up armies an order of magnitude bigger and comprising more than double the proportion of their population, you don’t have a “large” army, you have a moderately sized army. Ditto when there are peace time armies larger than your war time armies.

I tried to illustrate my point to the best of my ability, but this disappointing reply just highlights how absurd your narrative is.

There were large armies in Europe, but there was also a balance of power, and armies kept each other in check. Prussia could have an army of 187,000, but they could not commit a significant portion of their army to an American campaign without being invaded by their neighbors.

That's how a force that would be considered small by European standards of the time, could project significant military power circa 1776.

I never said that the Americans didn’t have the correctly sized force for their situation, I in fact pointed out that our numerically small armies were partially explained by weak neighbors. I was disputing the idea that we had a “large” army, which we for certain did not. You are correct in pointing out that “large” is not the same as “effective”, but that wasn’t the point I was making.

You are correct that European powers would have a very hard time projecting power over the Atlantic. If you had said that America was highly capable of defense because of its army and the high logistical cost of mounting an invasion across the Atlantic in pre-modern times, I would agree with you whole heartedly. France’s disastrous invasion of Haiti would also be a nice example to back this theory up too. But you said “large” and large in this context is an absolute without other qualifications (unlike say “effective”), which can be examined numerically.

What is large, exactly? If a large person was 1% smaller, would that person be still large? How doing this repeatedly and asking the same question each time?

In the context of North America in 1776, the American army was large. QED, have a good life.