When it was first built, what was the significance of San Antonio's location?

San Antonio was given its name on June 13, 1691, because that was the feast day of St. Anthony of Padua -- and the day that a Spanish expedition came to the river they called Rio San Antonio. But San Antonio was not founded until 1718, when its first mission and first presidio were established at San Pedro Springs.

Explanation:

united states reinforcements contributed greatly to three allied victories in france at: cantigny (first major american battle), argonne (the largest in the united states military history, involving 1.2 million american soldiers), and château-thierry (one of the first actions under general pershing).

to extend a country’s power and influence