What european country was responsible for the reintroduction of horses to the united states?

Spain

Explanation:

In 1493, Spanish horses first step on American land on La Espanola Island, today Saint Dominic, and are the direct ancestors of all American "Creole" horses. Once acclimatized to the new environment and increased its creation with subsequent imports, it quickly reproduced, in a few years, extended to the other Antilles and moved to the Continent. The wild horse, descended from horses brought from Spain to America, is a symbol of the Western United States, but its proliferation under protective laws has become a living space problem in the country.

the answer is they believed george iii would never give them their freedom.