In 1920, a little after noon, while crowds of businessmen were leaving their offices for lunch all along Wall Street, an unassuming horse and wagon exploded just outside the Morgan Building. Later analysis proved the bomb to be set with a timer and loaded with iron weights as shrapnel. Thirty-eight people were killed and hundreds more injured.

Bomb Blast in New York Sparks War on Terror The attack was a tragedy, but the overall desire was to return to "business as usual". With a bombing so close to the stock exchange, leaders were fearful of a panic, and so the damage was cleaned overnight. The board of governors for the stock exchange opened on the 17th without a problem. Rumors circulated that the explosion had been an accident. Soon, however, the Bureau of Investigation released flyers discovered in a nearby post office box with the cryptic message, "Remember. We will not tolerate any longer. Free the political prisoners or it will be death for all of you. American Anarchist Fighters!"

As the investigation continued quietly, people assumed it may have been an attack in reaction to the Sacco and Vanzetti, who had been arrested for murder in Massachusetts. People rallied behind the market in face of these "reds", and the celebration for Constitution Day continued at the same spot. Despite police surveillance, a package bomb exploded from a garbage bin, killing an additional seven. In Boston at the Farmer's Market, Washington, D.C., outside the Capitol, and San Francisco near the Mint, similar explosions followed.

The press seized the news, and the populace began to demand action. Wilson's term in office was nearly over, and the extremely ill president did not seem able to confront the issue of safety. Quoting the Washington Post, presidential hopeful Warren G. Harding said, "This is an 'act of war', and if it's war they want, it's war they'll get!" His words were dangerous in a world so soon after the Great War, but the gamble paid off, and he was elected in the largest majority since Washington. Immediately, Harding and his cabinet set upon establishing Security for Our Homeland. To prevent further plots, security checkpoints were set up at all train stations with passengers and baggage checked as well as bags being searched at important facilities such as museums, libraries, and public offices. Immigration came into heavy suspicion, especially as alcohol was run across the Canadian border, prompting many to call for a wall to be built.

Investigations pointed to Galleanists conducting the plot. All known accomplices were arrested on suspicion of conspiracy and spirited to federal penitentiaries. The leader, Luigi Galleani (pictured), had been deported to Italy, where he had been further exiled to an island and watched by government officials. Harding demanded that Galleani return for trial on conspiracy to commit murder. When the Italian government did not move quickly enough, he sent Marines to collect the anarchist personally. Foreign reporters described the action as an "invasion", but Harding refused to acknowledge that he had done anything beyond justice.

As his term progressed, Harding approached the League of Nations with evidence (which many critics said was scant at best) that the Bolsheviks of Russia had been responsible and were preparing more "actions of mass destruction". He encouraged other nations to redouble their support in the Russian Civil War, but if they refused, America would "do it alone". The Russian War, as it was called but never officially since Congress did not declare war, simply funded the American Expeditionary Force for Freedom. Many suspected Harding's administration of corruption, but most vocal opinions were drowned out by cries of patriotism.

Through the 1920s, the sense of panic would gradually subside in America while the war in Russia continued in a dogged fight against urban and guerrilla warfare. Many would call for a withdrawal of American soldiers by letting the Russian Republican Army defend the country itself, but neither Harding, Coolidge, nor Hoover fulfilled the promise to establish a timetable. The economy made a swift downturn in 1929, and Democrat Franklin Roosevelt in 1932 began the steady withdraw. America was ready for a time of isolationism, but the world dragged them back to action as the 1940s began the Second World War. Hitler's Fascists stormed Russia in 1941, citing the same principles of security Harding had and conquering it within a matter of months. Though over a million German troops would be caught up in the bloody occupation of Russia, further Germans would storm the beaches of Britain. Faced with overwhelming odds, the Allies would fight at tremendous losses until the tide of the war changed with the Atomic Bomb.

Beleaguered, economically depressed, and bringing up a generation calling for renewed isolationism, America would spend the rest of the twentieth century as something of an unwilling patron, constantly at guard for another attack by terror in a post-colonial world.