Guerrilla Warfare
The Tactic That Broke the World's Most Powerful Armies
The word 'guerrilla' was born in a war Napoleon was supposed to win in a matter of weeks.
The Idea
Conventional warfare operates on a logic of decisive confrontation — mass your forces, meet the enemy, break their will in a single catastrophic engagement. Guerrilla warfare inverts this entirely. The goal is not to win battles but to make winning the war unbearable: stretch supply lines, bleed morale, deny the occupier any clean target to strike back at, and make the cost of staying higher than the cost of leaving. What makes guerrilla tactics so persistently effective is that they exploit the structural weakness of powerful armies — their size. A large conventional force needs roads, food, ammunition, and communication. It moves slowly and predictably. A small irregular force needs almost none of this, which means it can disappear into terrain, population, or both. The asymmetry is the point. But there is a subtler insight here that often gets missed: guerrilla warfare is as much a political strategy as a military one. Mao Zedong, one of its most rigorous theorists, described the relationship between guerrilla fighters and the civilian population as fish to water — remove the water and the fish dies. The occupying force's inevitable overreaction to invisible enemies — collective punishment, civilian casualties, widespread surveillance — tends to generate exactly the popular resentment that sustains the insurgency. In this sense, the guerrilla fighter's most powerful weapon is often the enemy's own response.
In the World
When Napoleon invaded Spain in 1808, he expected a swift decapitation of the state and submission. What he got instead was something his military vocabulary barely had words for. After the conventional Spanish army was swept aside in weeks, the war did not end — it atomised. Thousands of small, autonomous bands operating across a vast, rugged country began harassing French columns, ambushing supply convoys, assassinating collaborators, and vanishing before reprisals could land. The Spanish called this the 'little war' — la guerra pequeña — and in doing so gave the world the word guerrilla. The French response was exactly what Mao would later describe as the insurgent's best recruitment tool. Brutal reprisals against villages suspected of sheltering fighters — immortalised in Francisco Goya's devastating painting series 'The Disasters of War' — hardened civilian resistance rather than breaking it. Napoleon ultimately deployed around 300,000 troops in Spain, a vast commitment that drained resources from other fronts. He later called it his 'Spanish ulcer,' crediting it as one of the primary causes of his eventual downfall. The Peninsula War lasted six years. Spain was never fully pacified. And the French, despite overwhelming conventional superiority, never found a way to fight an enemy that refused to stand still long enough to be defeated.
Why It Matters
Understanding guerrilla warfare reframes how we read almost every major conflict of the last two centuries — from the American Revolution to Vietnam to contemporary insurgencies. It makes visible a logic that conventional military thinking keeps getting surprised by: that raw power advantage does not straightforwardly translate to victory when the weaker side refuses to fight on the stronger side's terms. Beyond military history, there is a transferable idea here about asymmetric competition more broadly. The guerrilla principle — that you can survive and ultimately prevail by being elusive, cost-effective, and patient rather than powerful — has analogues everywhere from business competition to political organising to personal resilience under pressure. It also invites a harder question about the ethics of counter-insurgency: the very tactics that make irregular warfare effective tend to provoke responses that generate more fighters. Recognising this loop is not a counsel of pacifism, but it does suggest that military solutions to guerrilla conflicts have a structurally poor track record — and that the history bears knowing before the policy is made.
A Question to Ponder
If the most powerful side in a conflict so often struggles to defeat a far weaker guerrilla force, what does that tell us about what 'winning' actually means in war?
Get a new one of these every morning.
Start learning with Thinkable