“Mission Accomplished.” On 1 May 2003, George Bush stood under that banner and triumphantly announced the end of major combat operations in Iraq. Following the quick expulsion of the Taliban from Afghanistan, where the Soviet Union had failed after years of effort, it appeared that American military power was irresistible.

Looking back now, that scene seems drawn from another era. Combined with victories in the first Gulf war and Kosovo – when the US did not lose a single soldier in combat – it suggested a new level of military dominance.

“The revolution in military affairs”, it was called. Bombs were smart, armed forces were networked and the US owned the night.

All of which was very effective in defeating conventional armies or fanatics who had never encountered such weapons and tactics. But in its overconfidence, the US overlooked several things.

Like Napoleon, it underestimated the resentment many people feel at foreign occupation.

Napoleon had also achieved a revolution in military affairs, and consequently he was exceptionally effective in defeating armies in battle. His invasion of Russia, culminating in the occupation of Moscow, seemed initially like a stunning triumph.

But the people did not submit, and he had to abandon Moscow. With his army in retreat, his allies deserted him. He lost the war and was sent into exile.

Napoleon thought the message of French democracy would be welcomed. When France began to send its armies abroad following the revolution, its leaders thought they would be greeted as liberators. “It will be a crusade for liberty,” confidently proclaimed one of its leaders, Jacques-Pierre Brissot.

Not everyone was convinced. “No one loves armed missionaries,” responded Robespierre. But his caution, which proved prescient, was overruled.

This is an age of nationalism – an age effectively inaugurated by the French revolution. Ironically, the French revolutionaries did not understand their own time. Their military efforts to promote democracy were ultimately defeated by the nationalism of the people whose territory they occupied.

For the Russians, the war against Napoleon is known as “the patriotic war”. And the war against Nazi Germany is similarly known as “the great patriotic war”. Even the Soviet leaders knew that Russians were not fighting and dying for communism, but for Russia.

That reality challenges the effectiveness of America’s military superiority, just as it did Napoleon’s. The US armed forces are extremely effective at destruction. But the US does not want to destroy. Rather, it wants the threat of destruction to produce obedience.

What if that is not enough? It can escalate. The US can even kill people in cities in order to convince the remainder to yield to its superior power.

The US did it in the second world war – ultimately using atomic bombs – and there was no further resistance in Germany and Japan after the wars ended.

That is not an option now. To be sure, civilians are killed, but all efforts are made to try to avoid that. One of the military challenges confronting the US is how it can use its superior firepower in areas in which civilians are present.

The enemies it fights are not so restrained. Indeed, in Afghanistan, the other side specifically targets adults who dare to vote or young girls who seek an education.

Yet, despite the repulsiveness of these tactics, Taliban resistance has grown. US military commanders are warning about the deteriorating situation, and the Obama administration is bracing for a request for additional troops.

Can it be that the “revolution in military affairs” misunderstood war itself? Can it be that Americans convinced themselves that we could sanitise war, confine it to the “evil-doers” and thereby win almost effortlessly?

“It is well that war is so terrible – otherwise we would grow too fond of it,” Robert E Lee is reputed to have said at the Battle of Fredericksburg, during the American civil war.

Did Americans, intoxicated by successes, grow too fond of war? After Afghanistan, the Bush administration came up with reasons for invading Iraq, notably the threat from weapons of mass destruction.

But was that the most important reason? Or did the US go to war because war was regarded as easy?

If you are faced with a choice, and one of the options has advantages but no disadvantages, what do you choose?

We are now paying the consequences for misunderstanding war, for thinking it can be easy. There was no revolution. War is still terrible, and we should never forget it.