Many people have asked why the Roman Empire fell and usually they answer it themselves, so as to prove a pet theory or bring an end to the debate once and for all. I believe there are MANY answers to the question and that they all fit together, like a jigsaw puzzle. The reason I believe that is simple: History is a jigsaw puzzle of many causes and many effects, spurred on and brought about by the simple needs and wants of individuals. Let us start with the forest and work our way down to the trees. Let us start with the grand strategy of the Roman civilization. The type of government at the time, is at this point, is not an issue, but will be discussed.
Grand Strategy: The Legions of Rome
The Roman Republic started out as what historians call a 'Hegemonic Empire'. What that means, in basic terms, is that the Romans directly controlled a small area of land with their legions. Legions, as you know, can be thought of as heavy infantry armed with throwing spears, short swords and large shields. Surrounding this region, or linked to it by roads or sea-lanes, are small client states. These were smaller kingdoms that relied on Rome for protection and in return not only paid tribute, but also supplied the legions with food and auxilia (auxiliary troops). Auxiliary troops were cavalry, men armed with bows and slings, so on.
Outside the states are the tribes, some are clients to Rome and some are not. They were harder to control because of the distance from Rome and their own lack of organization, but some tribes are useful allies against other tribes.
The whole set up was pretty nice. Minor threats, like raiders, could be handled by the client states and the Rome never had to deal with it. Major threats, like invasion from Parthian Empire, could be handled by just bringing in some of the legions, which when added to the local auxiliary units, made a well-balanced defensive. In fact, legions plus auxiliary could be used for invading and annexing new holdings.
Why would client states allow this or even be happy with this relationship? Freedom from direct control was one. Yes, Rome had the power to replace kings, but by subjecting themselves to Roman diplomatic control smart kings got protection from other powerful nations and OTHER client states. For without the permission of Rome, no client state could declare war against another. Also, a King who proved himself valuable to Rome could call on legions to help put down revolts and civil unrest.
What did Rome get? Rome got trade, power beyond the direct reach of their legions and an empire at a tiny cost. Few legions were needed and most could be keep in reserve (what Edward N. Luttwak called disposable and concentrated imperial forces). The very fact these forces were available would make major powers think twice about invading any part of Rome's holdings. Thus, an elastic defense, flexible and cheap, also allowed troops for swift expansion. A young republic, full of men who needed military experience and money to hold office would do well in such a setting and so would Rome. Yet, when Rome became an Empire, or what is also called the Principate, the First Emperors (who were not called emperors just yet) wanted to consolidate Roman holdings. They turned to absorbing client states into provinces, campaigning against the Persians and even planned on taking all of Europe. Yet few pushed the borders farther than the Republic's lands before the Empire. They and the legions turned to defending the border, to keep what they had. They became, in other words, a 'Territorial Empire'.
A territorial empire is one that controls all territory directly, after either annexing or abandoning their allies. All forces are put on the frontier, to protect the border.
The problem with border defense (sometimes called forward defense) is the lack of flexibility. The basics are very simple. The legions, or most of them, are now on the border with provincial troops, who act like auxiliary units. This is great against minor raids by tribes who are trying to break into the empire. True, the legions are thinned out, but well placed forts, roads, walls and the use of natural barrier can really give them an edge even against three times their numbers. Tribes rarely carry rams or engines of war in their pockets and even a six-foot wall can cause problems. Men might get over it, but horses can't!
But what of major threats like invasions or revolts within the provinces? Few legions are in reserve, and therefore, the empire can only handle so many major threats before they become MAJOR problems. The Romans believed in economy of force and therefore, throughout most of their history had a fixed number of legions. This might be great at keeping costs down, but a change in the way the empire was run might have called for a change in the number of legions available. Rome and the emperors were not willing to make that change.
Also, a fixed line made out of forts and bases and walls causes problems. Early legions moved about, practiced and trained even in times of peace. They stayed tough and mean. Now they were held in barracks, within walls, dealing with health problems caused by the crowded quarters and loneliness. Some would go native, marrying and having families. Soldiers will want to spend time with family, over a good meal and good wine than on the practice field, tossing about spears and hacking at posts. The best would be taken away to Rome, to join the private armies of the Emperors (in other words bodyguards for the paranoid men on the throne).
How about the legions not guarding walls, but facing the Parthian Empire? These legions became just as undisciplined, as the leaders played about with improving the legions. They replaced legionnaires with more cavalry and foreign specialists. These men who were loyal to Rome, were loyal because of coins paid and promised wealth when they retired.
Also, let us not forget that peace itself can damage an army. Rome would bring periods of peace like no other civilization and even THAT might have been a problem.
That was only ONE cause. Let us examine another.
Army and Inflation: Another Day, Another Denarius
Here, we will focus not on weapons and equipment, but the men, both soldiers and generals. The first armies, or in this case, the first legions were invented by the last King (or Kings) of Rome. The legions were made up of the middle class, which was a political move to offset the power of the nobles. How it would help the King to have two power groups within the city I have no idea. But the idea stayed with the Republic. By 200 B.C. legions were made up of adsidui, citizens who owned property up to 400 denarii in value and able to support themselves financially. They were paid an amount of money depending on what branch of the service they joined, how long they served and if they volunteered more time. Some of their pay was used to pay for food and equipment.
The legions were well organized, broken down into smaller units with clear lines of command. Among the types of officers, early legions had six tribunes attached to it and being a tribune (tribal officer) brought great honor. Even an ex-consul could be a tribune. This showed links both to the Senate AND the people. Early legions could be disbanded at the end of a campaign, or if still needed to secure new land, only retiring soldiers were released. As the Republic grew and war sometimes-lasted longer, financial assistance was given to soldiers, no doubt to help them because of the increasing amount of time spent away from farms. Small campaigns, by 200 B.C., became full time wars and legions went from being part-time jobs to full-time careers, spanning several years.
Marius' reform in the late 2nd century B.C. greatly changed the legions. Not only did he change the structure, making it more flexible in battle, but he opened the ranks to the poorest of the poor and equipped them using state funds. These men, having no links to powerful families, now saw their family as their fellow soldiers and their loyalty was to the state and their leaders.
During the Civil War, which started in 49 B.C., both sides recruited from non-Romans and non-citizens. Pay was also doubled, no doubt to secure loyalty. After the war Augustus established a military treasury to handle discharge payments and made sure pay was under his control, not the generals. In his will he asked that the legions be fixed at 28 and that the Empire's borders also be fixed.
This may sound like pay was the biggest cost of the army, but let us not forget supply and transportation. Men had to be fed and therefore grain had to be shipped. Horses were needed, bridges and road maintained, equipment built. Sometimes the goal of the legions was nothing more than to collect tribute from a province.
Yet, pay raises happened a lot, sometimes doubling the soldiers' pay. Some historians believe the increases to be an emperor's way of buying loyalty or maybe of fighting inflation. Whatever the reason, here is the point we are getting at; Over the later centuries of the empire, while the number of legions might not change often, they become more and more costly. Luxury was believed by the Romans to destroy discipline and might have been a factor in the fall of their military in the last days of the empire. Extra coins in the pocket will make soldiers think of the good times they can have. Large discharge payments of either silver or land means a smart soldier is less likely to reenlist.
At the same time, when the empire did try to expand, it used up silver and gold, yet gained no new silver or gold mines to replace the old, exhausted ones. Its coinage, having started out as pure silver, now was less than pure. Britain had been invaded on the hopes of finding such treasure, but it was found to be worthless (no insult meant). For Rome to withdraw from a new province would be a sign of weakness. No matter how much it hurt to keep and no matter how many legions it tied up once taken a province was not to be given up without a fight.
You can see than, how inflation might make things harder on an empire whose borders have stopped expanding or when they do expand gain very little in value. Add an army that does not grow but whose paycheck does EVEN as the legions (mostly Non-Roman) become less useful and less skilled at the art of war, at best becoming either border guards or personal guards.
One more thing must be examined I believe.
Discipline: Stand And Deliver
Discipline. Why is it so important and why do I keep bringing it up, picking on the poor Roman legions again and again? Let us once again first examine the trees, than focus on the big picture.
Early Roman legions had many things going for them. They were always on the go, using roads, many of which they helped to build themselves. They also built fortifications around their camps, even when within friendly territory. Why?
By building a thin wall plus ditch around the tents, which were centered in the middle, they could get a good night's sleep, knowing fellow soldiers protected them. Also, spears thrown from outside were unlikely to hit the soldiers in their tents, which were carefully placed in the center, away from the edge of the camp. Nothing is worse than waking up to raiders stealing your stuff and trying to kill you. What is the result of a good night's rest?
The next morning, the soldiers are relaxed, well fed and ready for battle. Remember that battles in those days were lost when one side broke and fled. The side whose men were well rested and highly disciplined won the day. Discipline was a 24-hour job. Soldiers trained and were kept from becoming idle by building roads, setting up the camp's defenses each night and marching. Roman punishment was harsh. Some of the men in a legion could be whipped for ONE man running away in battle.
Now, picture yourself as an enemy nation. Early Rome has lots of legions (remember the reserves). You destroy one and take their standards. What does Rome do? They send more and more, because they want to save face and regain honor they lost. The legions are tough and hard to defeat in battle. They can and will win because sometimes they just won't FLEE.
Now, think of the later Roman legions. Few (in fact the same number just less available to use outside of the empire), undisciplined and a mixture of people who are not very Roman or even Italian. As an enemy nation, you are not as impressed and might even be able to bribe them or at least destroy the few legions Rome sends after you.
In the end, it does not matter if the people have orgies and get drunk. They were doing that in the time of the Republic and early Empire anyway. The problem starts when the legions start to lack discipline.
If that is not enough, lets talk about fear.
Fear: Dagger, dagger, who's got the dagger?
Fear was a tool, like any other. Rome used the fear of the legions, the overpowering military force of their unused reserve to not only keep tribes and equally powerful nations at bay, but also used it when dealing with allies. It was something that always hanged over the friend and foe alike during diplomatic talks. But it has limits.
German and Gallic tribes don't like being wiped out and fear death as much as anybody else. But during hard times, their children need grain just as badly as Roman children. The Romans and the defenses manned by their legions were great at defending against raiders and even punishing tribes, but they could never stop the never-ending waves that beat on their borders.
The great Parthian Empire of the east at first saw a great power. Roman legions could and did win wars and Romans were great at putting on a show after victory, building victory arches, and holding parades and games. In later years, as Rome started to find itself slowing down, its legions thinned out to protect the border of one of the largest empires known, its emperors corrupted (if not out right insane) and its coins only half silver, the east must have noticed.
Let's not forget the Emperors. Remember, 'what can be gained by the sword can be taken by the sword'. I am not sure who said it, but the Romans took it to heart. Emperors spent most of their time and money making sure the Praetorian Guard was happy and that the people of Rome were happy. As long as they had the throne, what happened in the empire was secondary. Fear of losing the throne overrode fear of losing the empire. If there was not assassins around the corner, the emperors had a habit of seeing them anyway.
The End: If Life is Wine, Why is everybody dead?
In the end, I am amazed it lasted so long. There are millions of tiny things I could add. There were Emperors who were totally insane and feared any man who showed the least amount of skill or intelligence in either running an army or running the government. There were Generals who marched on Rome with their legions, leaving the frontier to defend itself. The Games bled the empire as thousands died and free grain was given to the poor people of Rome to keep them happy. Slaves worked the empire's farms and factories and mines. I guess what we should really ask is; Why did it NOT fall earlier?
The Grand Strategy of the Roman Empire: From the First Century A.D. to the Third
By Edward N. Luttwak
Handbook to Life in Ancient Rome
By Lesley Adkins and Roy A. Adkins
The Roman Conquest of Italy
By Jean-Michel David, translated by Antonia Nevill
The Roman Empire
By Colin Wells
The Roman Republic
By Don Nardo
Rome and the Enemy: Imperial Strategy in the Principate
By Susan P. Mattern
Republican Roman Army 200-104 BC (Men-At-Arms Series)
By Nick Sekunda and Angus McBride
There are more books, which I only used parts of but I don't plan to list them all. God knows the spell checker already hates all the Latin words and authors' names. Also, I am sorry if I screwed up my Latin. I took it in high school and that was a long time ago.