Estrada Cabrera had survived multiple assassination attempts and governed through the absolute loyalty of his military. By declaring war on Germany during World War I, he acquired modern field guns, machine guns, and ammunition -- not to fight Europe, but to fortify his grip on Guatemala. What finally cracked his regime was not a bullet but an earthquake. The devastating tremors of 1917-1918 left Guatemala City in ruins, and the president's incompetence in leading recovery efforts turned public opinion decisively against him. On Christmas Day 1919, fifty-one citizens signed what became known as the "Three-fold Act" -- so named because the document had to be folded into thirds for covert distribution. The signatories founded the Unionist Party, headquartered in an Escamilla family home that quickly became known as the "People's House." For the first time, the Catholic Church joined the opposition, with the Bishop of Facelli preaching against government policies from the San Francisco Church. Students, labor associations, and conservative criollo leaders set aside their differences under a single banner.

On March 11, 1920, the Unionists organized a massive demonstration -- several thousand people marching on the Military Academy, where the National Assembly had relocated after the earthquakes destroyed its original chambers. The marchers demanded political freedom, press reform, and a new government. The Assembly had promised to receive them. Instead, the army opened fire with machine guns. Scores fell dead or wounded on the ground. Rather than crushing the opposition, the massacre unified Guatemalans against a president already detested after two decades of authoritarian rule. The whisper that had circulated for months -- that the whole country would side with the Unionists if necessary -- began to feel less like hope and more like prophecy. When Congress declared Estrada Cabrera unfit on April 8 and named Carlos Herrera as interim president, the streets filled with jubilant crowds. Herrera had been chosen partly because his personal wealth made him unlikely to steal from the treasury. Most soldiers, already bought off by the Unionists, simply watched from their barracks.

Estrada Cabrera answered the celebrations with artillery fire. On the morning of April 9, Guatemala City awoke to machine-gun fire and shelling from every quarter. From La Palma, French field-howitzers and seventy-fives pounded the capital, supported by the fortresses of San Jose and Matamoros. The Unionists were caught unprepared -- they had almost no weapons. They improvised with startling speed, plundering government buildings for arms and arming themselves with knives, machetes, shotguns, axes, and crowbars. Barricades went up across the city. Trenches were dug in the streets. White badges reading "Unionista" were distributed so fighters could tell friend from foe. Within hours, most men in the city wore them in their hats. The combat severed water lines and electrical cables, plunging the capital into darkness from the first night onward. Telephone and telegraph lines went dead. Red Cross vehicles dashed through the chaos, nurses riding on the running boards with medical supplies in one hand and a machete tucked in the belt -- ready to treat the wounded or defend themselves.

Among those trapped in the crossfire was Prince Wilhelm of Sweden, who had arrived in Guatemala City as a traveler and found himself barricaded in his hotel. The building's solid walls and corrugated iron roof withstood rifle fire and shrapnel, but barely. Guests stuffed earth from patio flower tubs into sacks for bomb shelters to protect women and children. They tore up old tram rails from the street to reinforce the roof, and barricaded the entrance with debris from a neighboring building that the 1917 earthquakes had already destroyed. When looters ransacked a store across the street but left behind a Venezuelan flag, the prince fashioned it into a crude Swedish flag and hung it from a hotel window -- claiming foreign legation status for the duration. The fighting dragged on for days, truces declared and broken within minutes. Soldiers deserted Estrada Cabrera's forces by the hundreds every night. When the garrison of San Jose fort was finally bought off, La Palma became indefensible. On April 14, Estrada Cabrera surrendered with his remaining five thousand troops and one loyal friend: the Peruvian poet Jose Santos Chocano.

The aftermath revealed the scale of what had happened. A shell had struck the Infant's Asylum, killing approximately thirty mothers and their newborns. Matamoros fort, built by Rafael Carrera in the Candelaria barrio simply because it was his birthplace, was found bristling with weaponry from Colt machine guns to 12-centimeter Krupp guns dating to 1877 -- along with a sign claiming four million rounds of machine-gun ammunition. Estrada Cabrera had possessed staggering firepower, yet his troops were starving -- not from lack of supplies, but from catastrophic mismanagement of the commissariat. Several hundred soldiers had been deserting nightly throughout the Tragic Week; those caught fleeing were executed on the spot by their own officers. The Unionist leaders, determined to restore democracy through law, fought off multiple attempts to lynch the former president at the Military Academy. They could not, however, prevent an angry mob from killing twelve Cabrera loyalists in Central Square, nor arsonists from burning the central railway station, sending smoke so thick it blocked the sun. Three days after the fighting ended, Guatemala City had resumed its normal appearance. There was no victory celebration. Citizens were too busy rebuilding, treating thousands of wounded, and mourning the 800 dead.