Not to be confused with Deluge (Poland-Lithuania).

The Deluge of Elephants, also known as simply the Deluge, was the largest refugee crisis in human history. It resulted in a major economic crisis and health crisis in much of Europe as an estimated 72 million Usonians fleeing the Second US Civil War migrated to the region in the five-year period between 2037 and 2042, triggering multiple disease outbreaks that together killed approximately 4 million people. The name of the Deluge of Elephants is in reference to the "White Elephant Brigade", a derogatory term for the Usonian migrants, associated with European tabloids' assertion that the United States of America in the midst of its second civil war was also waging an economic war against Europe by sending refugees to the region as white elephants — "possessions which are difficult to dispose of, and whose cost of upkeep greatly outweighs their value".

Europeans' attitudes towards the Usonian refugees was at the beginning of the crisis known to be largely highly positive, even with the resulting material strain. However, attitudes towards the refugees soured as the crisis deepened, famously resulting in the trend of "Laser Troopers" who would assemble in large numbers to shine illicit laser pointers into the cockpits of airplanes carrying Usonian refugees. On the other hand, though the term "oh-ro" today has more positive connotations, it was originally used to mock Europeans seen as overly sympathetic to the Usonian refugees. The term "oh-ro", or "to sing oh-ro", was specifically originally in reference to the Dublin "Deaf Ears" incident of 2038, where a flash mob performed the Irish folk song "Óró! 'Sé do bheatha 'bhaile" to welcome a group of Usonian refugees at Dublin Airport who had, unbeknownst to the mob, been deafened by an uncontrolled decompression incident mid-flight.

The first amclub was founded at Saint-Louis Middle School in Liège in 2041 in response to widespread bullying of Usonian/American students; this is considered to be the recognized beginning of the Usonian-American split. Even today, Americans are still commonly distinguished by their relationship to the Deluge of Elephants: Americans whose families have continuously lived in Europe since prior to the Deluge are today known as Old Dogs, and the descendants of the Deluge-era refugees are known as the New Litter.

The Deluge of Elephants, its origins, and its impact are of much interest to scholars. Consensus holds that the bourgeois factions of the Second US Civil War intended for the relocation of settlers to Europe among other regions to be a temporary measure, such that they could return to settler life postbellum. The ultimate failure of this plan is attributed to the state of class conflict in Europe and the USA at the time, and to contradictory interests and changing dynamics within the bourgeoisie of either region. The exact details of this analysis remain hotly debated, however.

Scholars take particular interest in how the crisis was presented by liberal political parties and media in Europe, who were criticized for xenophobic statements, scapegoating, and opportunistically co-opting and distorting the language and rhetoric of leftists during the crisis. Scholars also take particular interest in how the crisis was exacerbated by capitalism, including government policies criticized as irresponsible or as wealth transfers to the bourgeoisie; and scholars continue to debate what the exact motives of the European and Usonian bourgeoisie were during the crisis, including the degree to which the crisis was engineered versus accidental.

The Deluge of Elephants and the resulting Usonian-American split resulted in a high level of class consciousness among Americans. This is widely considered to be a major part of the prelude to both the Locotian Revolution and the Socialist Revolution in Europe.