Most Americans can’t comprehend battlefield slaughter on that scale. The largest battle on American soil was at Gettysburg, where about 105K of the Army of the Potomac faced off Lee’s Army of Northern Virginia with 75,000 men; losses were about 25K for the Union and 20K for the Confederacy. The two most costly battles of WWII for the US Army were the Battle of the Bulge, with about 105K casualties, including 19K dead and about 24K taken prisoner, and the Battle of Okinawa, with about 13K US soldiers killed, along with about 8,000 of the US Navy due mainly to Japanese kamikaze attacks. Compare those already grisly figures with the Eastern Front, of which Stalingrad was the most infamous, but certainly not the only major battle, with about 240K Germans either fallen in that battle or perished shortly after in captivity, along with about 120K of their allies; the Soviets lost almost half a million men in that great victory. Indeed, the casualties of the entire Eastern Front, possibly the bloodiest campaign known thus far, can only be guessed but most historians agree about 3.5 million German military dead, with about 500K of their allies (Italy, Romania, Hungary, and Finland), and at least nine million Soviet military dead (some believe as many as fifteen millions gave their lives in the “Great Patriotic War”).

The point of all that is that mass slaughter on the battlefield is known in our time; it’s more difficult to affix accurate figures for even battles well-researched like at Chalons-sur-Marne in 451 AD, where the Huns and their vassals were turned back in one of the last major victories for the Roman Empire (the Western part, anyway) along with their Visigoth and Frank allies. Jordanes, the Byzantine historian, claimed 250K dead total from both sides, with the fighting so vicious that the dead continued the battle in Hades. This figure has been well disputed due to the unlikelihood that either side could raise, train, provision, and supervise forces of that scale at the time. Trying to verify history of a peoples long gone, wherein even BoM scholars have no agreement as to where they lived, fought, and died, let alone utter lack of acceptance of the historicity of same by secular historians, is utterly impossible. One can only conclude that, to coin a phrase that Joseph Smith used over what appeared to be a biblical mistranslation, “Some old Nephite (Jew) put it there”, and that the true numbers are probably an order of magnitude off. Still, even 200K dead on each side would be an epic battle of antiquity. Or, in reading the text, it’s quite possible that both sides got everyone involved, even those that were not normally combatants…the women, the children, the elderly…anyone that could wield a club, point a spear, or throw rocks, as the “grand finale” was obviously genocidal in nature.

Many consider the population of seven billion people to only be possible now, in the 21st century, with the aid of modern medicine. However, remember that about 2.7 billion of those people reside now in China and India. A great portion of these populations live in rural areas, with less access to modern medicine.

Also, when considering that history, it’s important to know that things like war and disease often affected population numbers. The Black Plague is thought to have killed, at the high end, up to 60% of the population in Europe and the Mediterranean. That’s 3 out of every 5 people. After World War I, the Spanish Flu (which did not originate in Spain, for the record) affected 50% of the entire WORLD’S population, and killed between 50-100 million people in the space of a few years.

These are only two of the pandemics that have affected the world population, and there are certainly others of which we have little or no recorded information.

Since our current population is simply a multiplication of the numbers that previously existed, one can only imagine how many people would now occupy our planet if those diseases had never struck.

For starters, one of the big issues was, why didn’t they run away? This is key in answering your question! And the answer is they couldn’t! And this is one of the big downfalls of the Jaredites; slavery and human oppression.

Consider the following verses;

Ether 10:31 And he begat Heth, and Heth lived in captivity all his days. And Heth begat Aaron, and Aaron dwelt in captivity all his days; and he begat Amnigaddah, and Amnigaddah also dwelt in captivity all his days; and he begat Coriantum, and Coriantum dwelt in captivity all his days; and he begat Com.

Ether 7:7 And it came to pass that Kib dwelt in captivity, and his people under Corihor his son, until he became exceedingly old; nevertheless Kib begat Shule in his old age, while he was yet in captivity.

I could go on and on…notice the familiar theme here; Ether 11:18, Ether 11:19, Ether 11:9, Ether 11:23, and Ether 7:5.

This is a recurring theme and problem where the Jaredites rely on compulsion throughout all levels of their society from top to bottom. And this is why when certain groups fled through warnings from the Lord why they had to leave so early! In short, if they hadn’t fled beforehand then they wouldn’t have been able to leave later because of the repressive slavery and compulsion the Jaredites relied on in their societies.

Notice you also don’t see any mention of priesthood in the book of Ether. You see references over and over of the prophets warning them that they would be destroyed if they didn’t repent. But you see no references to Melchizedek Priesthood. This is also a sign of their practicing slavery.

(Also for people who question and attack the LDS church on accepting people of non-white origins this is also a good point to make. We have the Melchizedek Priesthood…freely given to us. And if we were practicing slavery we wouldn’t have had the chance to have the Melchizekek Priesthood! Yet people who come from ancestry of slave owners of the South and Eastern U.S. would attack us of accepting people of color. To have the Melchizedek Priesthood we would have to have accepted others! Our pioneer heritage and ancestors also treated the Indians well when we came to Utah. We didn’t enslave them.)

Back to the main point…

Its absolutely staggering how much you read…so and so dwelt in captivity in the book of Ether. And this is how they gained their wealth. Its very easy to see that if they’d do that for wealth of COURSE they would also use the same strategy for their armies, even down arming young boys and probably their women too when they saw how bad things were getting near the end of their civilization. Eventually they’d even threw their children into battle. (We have this thought because the civilization ended, thus there weren’t any more of them left. Why weren’t there anymore of them left? Because of these same thoughts.)

So in short, they weren’t allowed to flee the battles. They also had strong and mighty men (many scholars now think this means that there were giants among the Jaredites in their genes.) and that these guys would keep the others in check and be their leaders. It wouldn’t be hard to keep them in captivity and force them to all fight without running away this way.