Final answer:
The 1690 expedition led by Massanet and De León was aimed at protecting Spanish interests in East Texas from French settlers. This was part of Spain's broader attempts to defend its empire in America, which continued into the 19th century as American expansionists pushed into Texas, leading to the eventual Texas Revolution and annexation.
Step-by-step explanation:
The expedition led by Fray Damián Massanet and Alonso De León in 1690 was largely a response to concerns that French settlers were encroaching on Spanish territory in East Texas.
The Spanish Crown's efforts to protect its colonies from foreign powers, as well as the desire to convert native populations to Christianity, promoted such expeditions to assert Spain's dominion and prevent other European nations from gaining a foothold in the region.
This was part of a larger pattern of exploration, conquest, and settlement by Spanish explorers such as Hernando de Soto, who explored vast areas of the southeastern United States without finding the anticipated riches but left a profound impact on indigenous populations through the spread of European diseases and colonization.
Later, the Adams-Onís Treaty of 1819 established the U.S.-Mexico boundary, encouraging American expansionists to eye Texas as potential American territory.
Concerns over American settlement and expansion in Texas, in part also motivated by the establishment of a new American slave state, were ongoing issues for Spain and then Mexico, leading to subsequent events like empresario contracts to bring settlers to the region and ultimately culminating in the Texas Revolution and the annexation of Texas by the United States.