What external threat did NOT affect the early American republic?

The external threat that did not affect the early American republic is the expansion by Germany. During the formative years of the United States, particularly in the late 18th and early 19th centuries, Germany was not a unified nation-state but rather a collection of independent kingdoms, duchies, and city-states. The significant geopolitical events that involved the United States during this period included conflicts with Native Americans, tensions and military engagements with the British, and the military campaigns against Mexico. These events are well documented and had direct impacts on the shaping of the early republic.

In contrast, Germany's unification did not occur until 1871, long after the key formative events of the early American republic. Therefore, any threat or expansionist ambitions from Germany played no role in the early challenges faced by the United States in its establishment and early governance. This historical context makes it clear that the other options listed represent real challenges that confronted the fledgling nation at that time.