As the first rumble of the Great War's cannon fire reached the New World, there had already formed a decisive bloc opposing American belligerency. It included ethnic groups, such as Irish and Eastern European immigrants who had grievances against some of the Allied powers; gatherings like the Progressives, suffragettes and prohibitionists who were more interested in pursuing their causes than waging war; and Westerners and farmers who did not feel any affiliation to Europe. These anti-interventionists were buttressed by the long American tradition of noninvolvement in the political affairs of the Old World and by President Wilson's early, insistent declaration of American neutrality.

Nevertheless, as the World War unfolded, these "doves" had to face novel and confounding events that forced them to reevaluate their positions. Remarkably, almost every major incident that followed the war's early days had the effect of pushing, pulling and even seducing some segment of America into joining the originally minimal pro- intervention coalition.

The German Army, embodiment of "Prussian militarism," quickly acquired a "beastly" reputation by administering occupied territories ruthlessly, executing nurses and bombarding medieval Louvain library and Rheims cathedral. Their actual misdeeds were magnified by Allied propaganda, and by Germany's inability to make their case directly to the American public. The Royal Navy had not only blockaded the Central Power's maritime commerce, but had also severed Germany's transatlantic cable. In the US, these factors contributed to the early "demonizing" of Germany, its legions and Kaiser Wilhelm. Liberals in particular began to see their dreams of a world of justice based on peace, democracy and non-monpolistic markets threatened by the existence of the kaiser's regime. Thousands of them felt so strongly that they enlisted in Allied armies and ambulance services. Pacifists, in their turn, evolved the paradoxical position that true peace could be found only after German militarism was eradicated.

By 1915, Allied contracts for weapons and food triggered a boom in the United States. Then, as the Allies hard currency reserves ran out, huge loans were floated to finance their purchases. Many Americans, from factory workers to farmers to investors, came to have a not-fully-recognized, economic stake in an Allied victory. Because of the naval blockade's success, similar economic links never developed with the Central Powers. The ultimate role of economics in American intervention is still hotly debated, but it is an issue whose importance cannot be ignored.

The sinking of the British passenger liner Lusitania in the spring of 1915 resulted in the deaths of 1,195 persons including 128 US citizens. The ensuing diplomatic hullabaloo was one of the major landmarks of America's journey to the Great War's battlefields. Some lesser-known side effects -- probably underestimated later by the German General Staff -- edged the country further towards effective intervention. Many persons, including some still opposed to intervening, came to realize they were willing to fight for their country if German actions compelled America to enter the war. A war preparedness movement was triggered that succeeded in boosting US military capability, training a larger officer cadre and improving mobilization planning. Later problems along the Mexican border both heightened awareness of impending hostilities and showed the shortcomings of existing logistical systems. Most importantly, all of this re-awoke the nation's dormant martial spirit and esteem for its military heritage.

As its years of bloody carnage dragged on, the war started to exercise a gravitational pull on US domestic politics. Many activists began to see benefits from participating in the war since a nation on a war footing may undertake, out of urgency, social and political changes that it normally would not. Anti-capitalist elements, for instance, recognized possibilities for more government controls over industry. Advocates of redistributing wealth saw in any war's undoubtedly great expenditures a necessity for imposing an increasingly progressive income tax. Wartime rationing might offer prohibitionists a chance to impose their favorite method of human betterment on the citizenry. Unions saw that a war meant jobs for their members, just as it meant more contracts for the corporations. No one was brazen enough to call for war to satisfy private ambitions, but some Americans became aware that if the country was drawn into war, they might advance their interests.

Concurrently, the anticipated opposition of immigrant groups to participating in the war seemed to dissolve. In the early twentieth century, America was in the midst of the greatest wave of immigration any nation has ever absorbed. Fearing political instability, politicians like Wilson and Theodore Roosevelt felt it necessary to speak-out with disapproval against "hyphenated Americanism" such as Polish-Americanism or Italian-Americanism. But the newcomers all proved uniformly loyal to their adopted nation and its causes. Except perhaps for German-Americans, who hoped to avoid fighting their cousins and lobbied likewise, ethnic-centered opposition to entering the war never became a major factor. People of every heritage, including those of German ancestry, rushed to serve under US colors when war finally came.

Public opinion in the United States was dramatically shifting towards intervention throughout 1916. But there was another, Constitutionally empowered, player yet to commit his hand. The President, commander-in-chief of the armed forces, has to support wholeheartedly any war that America plans to fight. No country can expect to succeed in battle with an irresolute, reluctant captain.

For most of the Great War, Woodrow Wilson had seemed to be the most unwilling of war lords. But he had also come to see that his nation's only opportunity to influence the postwar international realignment might be at the peace conference after hostilities ended. And Wilson's multiple unsuccessful efforts at playing peacemaker had educated him to the fact that a seat at the conference table first required some sacrifice on the battlefield.

But he also shared his countrymen's customary reluctance to join a European conflict -- a tendency reinforced by his political instinct not to get too far ahead of his constituents. During the 1916 presidential campaign, and even into early 1917, he did not feel that the nation was ready to go to war. Still of two minds about American involvement, himself, the President required more direct provocations before taking advantage of the growing support for participation. On January 22nd, he made a last plea to the combatants as an 'honest broker' with his "Peace Without Victory" speech to the Senate.

Germany announced resumed unrestricted submarine warfare at the end of January 1917. Most Americans considered this an unacceptable limitation on freedom of the seas. Diplomatic relations were severed. As US flagged vessels were sunk, emotions heightened.

Then came German Foreign Minister Zimmerman's notorious "Telegram" to his ambassador in Mexico. This message, intercepted by British code-breakers and released at an opportune moment for the Allies, suggested a Mexican, German and even Japanese alliance against America. If successful, it was suggested, this could have resulted in the return of Texas, New Mexico and Arizona to Mexico. The Zimmerman Telegram caused another uproar, particularly in the western states. Yet even as calls for war from Congress grew louder, the President kept his own counsel.

Finally, an event in mid-March that shook the world removed the final impediment to Wilson's opting for war. Revolution in Russia forced the ineffectual autocrat, Tsar Nicholas II, to abdicate. When the Provisional Government assumed authority, America and Mr. Wilson could profess to be crusading with apparently democratically-inclined associates, exclusively.

Every major social and political obstacle to American involvement in the war had vanished. A national belief that it was in America's own interest to vanquish Germany and save civilization was ascendent. Germany's heavy-handedness and the tsar's overthrow had allowed Wilson to place his remaining qualms aside and pursue a "world safe for democracy". He had only to ask Congress to declare war and the nation would be ready to march.

On April 2nd, Woodrow Wilson -- who five months earlier had been reelected with the help of supporters cheering, "He kept us out of war!" -- rode to the Capitol and asked Congress to declare war on Imperial Germany. Only 56 of 531 congressmen and senators objected and on April 6, 1917 America was at war.