Meanwhile in Haiti, outrage followed outrage and coup followed coup. American financial interests were threatened and, worst of all, there was a danger that some other power might act first.
'The more I think about that situation,' wrote President Woodrow Wilson early in 1915, 'the more I am convinced that it is our duty to take immediate action. I mean to send commissioners there who will say to them as firmly and definitely as is consistent with courtesy and kindness that the United States cannot consent to stand by and permit revolutionary conditions constantly to exist there.'
No sooner was this warning delivered than the government which heard it collapsed in further bloodshed. Threats alone, it seemed, were useless.
Foreign powers were stirring up unrest. French warships were calling at Haitian ports, right in America's back yard. The British were interested, and the Germans had more than once interfered, either by lending money to rebels or with gunboats. Haiti might become caught up in the European war. It was time to act.
Yet still the President dithered, fretting about legalities. In the end, it was events that forced the American hand, events of a particularly gruesome kind.
Rear-Admiral William Caperton of the US Navy's Atlantic Fleet was aboard the battleship USS Washington, calling at the various Caribbean trouble spots to show the flag and gather intelligence. When he arrived at Port-au-Prince harbour at the end of July 1915, Caperton witnessed through his telescope a strange commotion on the dockside.
President Guillaume Sam, in power for just a few months, had been dragged out of hiding in the French Legation by a mob following the massacre of 130 political prisoners in the city jail. Now he was being dismembered. Jubilant rioters were emerging from the scrum with a hand, a foot or the head, and dancing off down the street, while the trunk was bound in chains and, to enthusiastic cheering, dragged back and forth along the docks.
Caperton sent in the troops: 330 marines and sailors, who landed unopposed and took up position in the marketplace, outside foreign legations and at other key points in the capital. The townsfolk were hostile and the soldiers, keenly aware of Haiti's voodoo traditions, were tense. Two Americans were killed by sniper fire in the darkness, but by morning it was clear that the orgy of violence was over.
Caperton now faced a decision. While his soldiers disarmed the populace, carrying off guns and ammunition by the waggonload, he began talks with the nearest thing he could find to a government: a collection of local grandees calling themselves the Revolutionary Committee. This body promptly nominated as the new President Rosalvo Bobo, the most anti-Yankee politician in Haiti, but Caperton was able to block Bobo's path. He was later to lament of local politics: 'It was a very maze, a crazy quilt of a state of affairs.'
Back in Washington, Woodrow Wilson - the president remembered as the champion of national self-determination - gave his belated blessing to the invasion, saying: 'I suppose there is nothing for it but to take the bull by the horns.'
He now wanted to see stable democracy in Haiti, and by his definition (whatever the Haitians wanted) that meant a government pleasing to the United States.
'We must let the present (Haitian) Congress know that we will protect it but that we will not recognise any action on its part which does not put men in charge of affairs whom we can trust.'
This was to prove an impossible formula. Caperton had said the occupation would be 'of short duration', but it was not. All efforts to implant democracy failed, not least because the occupiers demonstrated shocking racism in their dealings with the Haitians, and because Washington refused to let go of the purse strings.
When the US finally pulled out in 1934, they left behind an unintended legacy. Francois 'Papa Doc' Duvalier was by then active in politics, peddling the potent xenophobic ideas that, two decades later, helped him become the most notorious of all Haiti's dictators.
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