The republican era saw an end to colonial settlement, but not migration. Its early years were extremely promising for the poor and tired of the world. Still, this wasn't significant until one event: the Weltkrieg, also known as the Great War or the First World War. The destruction caused in Eurasia triggered a massive migration wave from all of Western Europe, the Mediterranean and Eastern Europe. Most importantly from France, Belgium and Britain which saw huge social disorder or German occupation. Russia was also a high exporter due to the Bolshevik Revolution and the destruction it caused. While Oceanyka was less appealing than America as a migration point, it did see around twenty million migrants and war refugees arriving.
Fourth Great Wave migrants were hard-working middle-to-low class people. Businessmen, clerks, engineers who had lost their jobs; farmers and miners who had lost their land. They came for a new opportunity.