Tsunamis generated by that eruption killed 40,000 on Java and Sumatra. The explosion was heard as far away as Australia and India, and threw millions of tons of ash into the atmosphere that affected global weather for years. Krakatoa's ash helped cool temperatures around the world and led to stunning sunsets in Europe and the US that captivated artists.
The 1815 eruption of Mt. Tambora, too, had far-reaching effects. It killed 100,000 people on Sumbawa island and spewed so much ash into the air that 1816 became known in the US and England as "the year without a summer."
In Europe, Mary Shelley penned her grim tale of Frankenstein while huddled inside that year, and her literary friend Lord Byron wrote, "the bright sun was extinguish'd..., and the icy earth swung blind and blackening in the moonless air." [Editor's note: The original version may have led the reader to believe Shelley and Byron wrote in the year 1883 instead of the correct year of 1816.]
Some historians say that crop failures in New England that year spurred an exodus of tens of thousands of farmers to more-fertile soils of the Midwest, speeding the American conquest of the continent.
Imams on the northwest coast of Java preached that the eruption was a sign of Allah's displeasure at infidel rule, and urged a violent jihad, according to Sartono Kartodirdjo, am Indonesian historian.
The Dutch knew the political stakes, and knew that improved global communications would bring unprecedented scrutiny to the disaster, says Mr. Winchester, by phone from his home in England.
"The Dutch made this superhuman effort to bring relief to the area because they were aware of the significance of the event and that the Muslim clerics were quickly making political capital from the event," he says.
Nevertheless, emboldened clerics and destitute peasant communities sharpened their rhetoric and began an assassination campaign against Dutch officials and planters, culminating in the Banten peasants' revolt of 1888 that killed dozens of Dutch and hundreds of Indonesians.