The conflicts initiated by France left the colonial empires in the New World dangerously exposed, accelerating a collapse of imperial authority across the Western Hemisphere. In British Mornaea, the Crown’s total focus on the European theater led to decades of neglect, leaving the mainland colonies defenseless and economically stifled. This vulnerability was brutally exploited in 1812 when the Dutch launched an invasion of the southern colony of Philippia to destroy its cotton industry. With no British garrison to protect them, the colonists hired the "Green Confederacy"—a powerful alliance of industrialized native states—to wage a proxy war of retaliation against the Dutch colonies. This sparked a vicious cycle of raids and massacres, culminating in the slaughter of a Dutch garrison at Zeist, which shattered the economy of the Dutch "Zudland" colonies and drove them to declare independence from the Netherlands in 1815.

The Netherlands attempted to reconquer its rebellious southern provinces, but the "Liberation War of the South" ended in disaster with the fall of New Amsterdam to rebel forces in 1818. Bankrupt and exhausted, the Dutch government signed the Treaty of The Hague in 1819, recognizing the independence of republics like Grootland and New Brabant. Desperate to liquidate assets, the Dutch subsequently sold the vast, indefensible "Groot Territory" to the United Provinces of Mornaea (UPM) in 1820. This acquisition allowed the UPM, now a stabilizing power under the "Years of Harmony" of Emperors Mingxi and Mingyue, to expand its dominion from the Pacific to the interior, cementing its rise with the construction of a new, centrally planned capital at Pingcheng.

For Britain, the loss of its mainland colonies was a gradual, quiet disintegration rather than a violent revolution. Throughout the 1810s, the colonies on the eastern seaboard drifted into de facto independence, ignoring royal decrees and developing their own militias and governance. When Britain finally attempted to reassert control in 1820, its officials were barred from entry. Faced with a hostile colonial populace, King Henrik refused to authorize another costly war. Furthermore, Parliament rationalized the loss by accepting the rising UPM as the new "heavyweight" of the continent, calculating that the Han Republic posed no immediate threat. Consequently, Britain formally recognized the independence of its former colonies south of New Britain in the Treaty of Springchester in 1822, birthing a collection of independent states ranging from the industrial Commonwealth of New Dorset to the agrarian State of Philippia, whose flagging cotton economy was soon revitalized by the invention of the cotton gin.

In the southern continent of El-Rabeeah, the collapse of the Madjriti Empire was far more violent. Driven by the Sultanate’s insatiable need for tax revenue to fund its global wars, the colonies of Emberland and Imberia rose up in 1810 in a massive revolt known as the "Continental Liberation." Unlike the British, the Sultanate attempted to crush the independence movement with total war, leading to a bloody twelve-year conflict that devastated the region. By 1823, Madjrit was forced to accept the loss of its most lucrative possessions, resulting in the emergence of three new, ethnically diverse empires: Emberland, Azimland, and Imberia. These wealthy but unstable states, forged in the fires of the "Duplicitous War," marked the definitive end of Old World hegemony in Mornaea and El-Rabeeah.