The Geopolitics of Guano: How Bird Poop Sparked Wars and Built Modern Agriculture

History14 min

A small island crusted white under a few seabirds, with a laboratory flask rising behind it like a sun.

For about thirty years in the middle of the nineteenth century, one of the most strategically important places on earth was three small islands off the coast of Peru. They are rainless and treeless, and they were buried under mounds of bird droppings as much as 150 feet high. Governments wrote that stuff into presidential addresses. Navies sailed to take it. The United States passed a law that let any citizen annex a rock on its behalf if the rock was covered in it.

The usual way to tell this story is as a comedy: the world went to war over poop. That framing gets two things wrong. It undersells how serious the problem underneath was. And it oversells the wars, which were mostly about other things, with guano as the reason they were worth fighting. What the guano age actually shows is what happens when an entire civilisation’s food supply hangs on a single non-renewable deposit in someone else’s territory. That situation ended in a lab in Karlsruhe rather than on a battlefield, and I think it is the more interesting ending.

§A nitrogen problem pretending to be a farming fad

Crops need nitrogen in a form they can use, and there is never enough of it. The air is almost four-fifths nitrogen, but it is locked in a triple bond that plants cannot break, so for all of agricultural history the supply came from slow biology: legumes, manure, rotation, letting a field rest. Every farm was capped by its own nitrogen budget.

Peruvian guano broke the cap. The coast is so arid that nothing washes the nitrogen out of the droppings. Tens of millions of cormorants, boobies and pelicans living off the small fish of that coast had been piling it up for centuries. People in the Andes had known what it was worth for a very long time: the word comes from the Quechua wanu, and the Inca are said to have made killing the birds a capital crime. Europe and North America caught on in the 1840s, and the response was less a market than a mania. American growers in the South talked about a “guano gospel”.[2]

By December 1850 it had reached the State of the Union. Millard Fillmore told Congress that Peruvian guano had become so desirable an article to the agricultural interest of the United States that the government had a duty to get it imported at a reasonable price.[1] That is a head of state telling his legislature that the price of a fertiliser is a national-interest problem. Swap the noun and the sentence could be about oil in 1973 or rare earths today.

From a systems point of view, guano had every property of a dangerous dependency. It was concentrated, with the best deposits on a handful of islands. It was finite: birds lay it down over centuries and ships carried it off in a few decades. And it was controlled by one seller who ran it as a state monopoly.

§The state that ran on a stockpile

Peru used the guano as collateral for a state. The government owned the deposits, sold the product through foreign merchant houses, and borrowed in London against the future revenue, so heavily that London’s banks ended up effectively controlling the trade. The economist Catalina Vizcarra has described Peru as an oddly reliable debtor: it kept pledging guano income to foreign creditors while it went through fourteen changes of government between 1850 and 1875.[2] Governments came and went, and the debt service kept running, because the guano was the one thing in the country that worked.

Revenue that comes out of the ground instead of out of a taxed population has a familiar shape. It frees the state from needing the consent of its citizens, it invites borrowing against the next decade, and it goes to pieces when the deposit runs out. All three happened. Exports fell from about 575,000 tons in 1869 to under 350,000 tons by 1873, and the Chincha deposits were essentially gone by 1874.

I don’t want to tell the next part as a fun fact, because it is the part the comedy version leaves out. Somebody had to dig, by hand, through ancient mounds of ammonia-reeking dung under a desert sun. The work fell largely to Chinese indentured labourers, the “coolies” of the period’s own vocabulary, some of them kidnapped and others recruited with stories that they were going to California. Many killed themselves rather than go on.[2] In the 1860s, ships from Peru raided Polynesian islands for labour, and some small islands lost a large share of their people. You will find precise death tolls for the Chincha workforce quoted all over the internet. The ones I could trace lead back to a single nineteenth-century encyclopaedia entry, so I am not repeating them. The conditions are documented well enough without a number I can’t stand behind.

An editorial irony was noticed even at the time: American Southern papers publicised the slave-like conditions on the Chinchas while running no such reports about slavery at home.[2] People find it easy to see coercion in a supply chain when it isn’t their own.

§Which wars were actually about guano

So did guano spark wars? Partly, and the details matter.

The Chincha Islands War (1864–1866) is the one with guano in its name, and even that one did not start over guano. It started over a brawl. On 4 August 1863, a fight at the Talambo hacienda in northern Peru left a Spaniard dead. Spain, under a government keen to recover some imperial standing, rolled that together with unpaid debts from the independence era and demanded satisfaction. On 14 April 1864 a Spanish squadron seized the Chincha Islands.[3]

Look at the choice of target. Spain did not invade Lima. It took the one asset that, by the common estimate, produced something like 60 percent of the Peruvian state’s revenue. That isn’t a war for guano. It is a war fought with guano, the islands held hostage the way you would seize a debtor’s bank account instead of his house. It worked, briefly. Peru’s president signed the Vivanco–Pareja treaty in January 1865, the Peruvian Congress refused to ratify it, and he was overthrown. The conflict then spread. Chile declared war on Spain in September 1865, and Spanish ships bombarded Valparaíso on 31 March 1866 and fought the batteries at Callao on 2 May. Both sides claimed Callao as a victory, and the final peace treaties were not signed until 1879 to 1885. Guano was the leverage, and pride and old debts were the cause.

The War of the Pacific (1879–1884) is the bigger and bloodier one, and that war was about nitrates, the mineral successor to guano. The Atacama desert, on the borders of Peru, Bolivia and Chile, is full of caliche, an ore rich in sodium nitrate, which is useful both as fertiliser and as an ingredient of explosives. The trigger was a tax. An 1874 treaty set the border and promised Chilean companies in Bolivian territory 25 years without new taxes. Bolivia then imposed a ten-centavo tax on the Chilean-owned nitrate company at Antofagasta, and in the dispute that followed it seized the company’s property and set it for auction. Chile occupied Antofagasta on 14 February 1879, the day of the auction. Peru was tied to Bolivia by a secret alliance from 1873, and it was drawn in.[6]

This is where the threads join, and it is the strongest version of the headline’s claim. Peru was in the nitrate business in the first place because its guano revenue was collapsing. To replace it, Lima created a nitrate sales monopoly and, in 1875, expropriated the nitrate works in its own province of Tarapacá. Guano’s decline pushed the Peruvian state into nitrates, and that put it on a collision course with Chilean companies backed by British money. The London house of Antony Gibbs & Sons had supplied roughly a third of the capital of the Chilean nitrate firm that preceded the Antofagasta company, and it also held shares in Peruvian nitrate works. The City had money on both sides. Chile won comprehensively. Lima was occupied in January 1881. The Treaty of Ancón (20 October 1883) gave Chile Tarapacá, and the 1884 truce cost Bolivia its coastline, which it has never got back.

So the honest tally is one war that used guano as a hostage and one war over the commodity that replaced it, started in part by guano’s exhaustion. Neither was simply fought over bird droppings, and both make sense only once you see that for half a century the Pacific coast of South America was where the industrial world bought its nitrogen.

§Annexation by paperwork

The United States answered the Peruvian monopoly with one of the strangest statutes in its code. The Guano Islands Act of 1856, which William Seward introduced in the Senate, says that when a citizen finds guano on an island not within the lawful jurisdiction of any other government and takes peaceable possession, the island may, at the President’s discretion, be considered as appertaining to the United States.[4]

“Appertaining” is doing heroic work in that sentence. It is not annexation, it is not statehood, and it doesn’t even quite make the island a territory. More than seventy islands were eventually claimed under the Act, and the State Department itself concluded in 1932 that no one knew what the Act really meant.[2] It was imperial expansion as a software licence: the company gets the rights, the sovereign keeps deniability, and the terms are vague enough to mean whatever Washington needs them to mean later.

The vagueness was tested on Navassa, a Caribbean island off Haiti that Haiti also claimed. On 14 September 1889 the island was worked by the Navassa Phosphate Company, and the evidence recited by the Supreme Court counts 137 Black labourers working under company officers. The workers rose against their overseers, and five of the overseers were killed. A labourer named Henry Jones was tried in the federal court in Maryland for one of the killings and appealed on the obvious ground: what right did a US court have over an island that the US had never properly annexed?[5]

The Court refused to look. Who is sovereign over a territory, Justice Gray wrote, is not a judicial, but a political, question, and the executive’s determination binds the judges. The President said Navassa appertained, so it did. Three workers were condemned to death, and President Harrison commuted the sentences after public criticism of conditions on the island.[2] The legal manoeuvre outlived the fertiliser trade by a long way. Christina Duffy Burnett’s reading is that it helped set the stage for how the United States took and governed the Philippines, Puerto Rico and Guam a decade later.

§The chemist steps in

By the 1890s the anxious people had moved on from guano to the Chilean nitrate beds, and done the arithmetic. On 7 September 1898, William Crookes used his presidential address to the British Association in Bristol to warn that the wheat-eating world was heading for a nitrogen famine. Guano, he said, was so near exhaustion it could be dismissed from consideration, and cautious local estimates gave the Chilean nitrate fields twenty to thirty years at the then export rate of over a million tons a year. His way out was not a navy. He predicted that the chemist will step in and postpone the day of famine.[7]

He was right, and quickly. In July 1909 Fritz Haber demonstrated a bench apparatus at Karlsruhe that combined nitrogen from the air with hydrogen over a catalyst at high pressure and dripped out liquid ammonia for about five hours straight. Scaling that up was another matter. BASF’s head of research was horrified at the idea of running a plant at a hundred atmospheres, having just watched an autoclave at seven blow apart. Carl Bosch, who was running the company’s nitrogen work, answered with a line I love for its engineer’s confidence: he knew exactly what the steel industry could do, and It should be risked. Commercial ammonia production began on 9 September 1913, four years and two months after the lab demonstration.[8]

Then came the dark joke. Within a year the process was strategic in exactly the sense guano had been. When the war began, the British blockade cut Germany off from Chilean nitrate, and synthetic ammonia is generally credited with keeping Germany supplied with both fertiliser and munitions.[9] Haber himself went on to run the German gas programme and oversaw the first chlorine attack at Ypres in 1915. He received the 1918 Nobel Prize in Chemistry for the synthesis of ammonia from its elements, and Bosch shared the 1931 prize for high-pressure methods.

The geopolitical consequence is the part I find most clarifying. Once nitrogen could be made from air plus energy, there was nothing left to seize. You cannot hold a hostage that every industrial country can manufacture at home. The Chilean nitrate fields, which Chile had fought a war to win, were now competing with a factory that could be built anywhere there was coal, steel and engineers. Vaclav Smil’s estimate is the one usually quoted for what was at stake: without Haber–Bosch, almost two-fifths of the world’s population would not be here.[8]

§Dependencies end in labs, not on islands

The lesson I draw is not that commodities cause wars. Plenty of wars happen without commodities, and the guano wars needed Spanish pride and a Bolivian tax bill to get going. The lesson is narrower and more useful: a strategic dependency on a concentrated natural deposit is a temporary condition, and what ends it is almost always substitution rather than conquest. Spain held the Chinchas for months and got nothing lasting. Chile won the nitrate war outright and saw the prize made obsolete by a high-pressure reactor in the Rhineland. The countries that actually escaped the nitrogen bottleneck did it with catalysts, not cruisers.

Substitution has its own costs, and they are worth naming. Haber–Bosch swapped a geographic chokepoint for an energy one: most of the hydrogen now comes from natural gas, so the world’s food supply is now tied to gas prices instead of bird colonies. That is a better problem to have, and still a problem. And the people who paid for the old system, Chinese labourers on the Chinchas and the workers on Navassa, got nothing back when it ended. Their labour simply stopped being needed.

Guano also belongs to a wider pattern on this site. The commodity was only half the machinery. The other half was paper: merchant contracts, London bond issues, a revenue stream pledged across fourteen governments, and an island annexed by one ambiguous participle. If you want the older history of how ledgers and credit let merchants move value across distance, that is The Paper Route. And if you want what happens to whoever controls the wires the prices travel over, that is Information Monopoly. The birds are still out there, though not many of them. Peru went on mining guano for its own farms in the twentieth century, the fish the birds eat have thinned out too, and an estimated 60 million seabirds have become about 4 million. The deposit that frightened presidents now amounts to something like 12,000 tons a year.

  1. ^Millard Fillmore, First Annual Message, 2 December 1850, The American Presidency Project.
  2. ^Matthew Wills, “Are We Entering a New Golden Age of Guano?”, JSTOR Daily, 2016. It draws on Weymouth T. Jordan on the American “guano gospel”, Catalina Vizcarra on Peru as a debtor state, and Christina Duffy Burnett on the Guano Islands Act. Gregory Cushman’s Guano and the Opening of the Pacific World (Cambridge, 2013) is the full-length treatment.
  3. ^On the dates and on Spain’s motives, the Chincha Islands War summary is a reasonable starting point. It also gives the much-repeated estimate that the islands supplied almost 60 percent of Peru’s government revenue. Treat that figure as an order of magnitude, not as an audit.
  4. ^48 U.S.C. § 1411, from the act of 18 August 1856, Cornell Legal Information Institute.
  5. ^Jones v. United States, 137 U.S. 202 (1890), full opinion. The facts about the island’s population and the date of the killing come from the evidence recited in the opinion.
  6. ^The causes, the dates and the Gibbs capital are summarised, with references to the historiography, in War of the Pacific. Historians still argue over how much weight Chilean economic crisis and elite interests should carry.
  7. ^William Crookes, The Wheat Problem, the presidential address to the British Association at Bristol, 7 September 1898, reprinted in a later revised edition.
  8. ^Vaclav Smil, “Detonator of the population explosion”, Nature 400, 415 (1999). The Nobel Foundation’s entries for Haber (1918) and Bosch (1931) give the prize details.
  9. ^Fritz Haber, Science History Institute.