When the British evacuated Pensacola, McGillivray turned to Spain to stop the advance of the Georgians into Creek country and urged that the Scottish firm of Panton, Leslie and Company, later known as John Forbes and Company, continue the lucrative Indian trade in Spanish territory.

Operating near the Flint-Chattahoochee junction, a license was issued to the firm in 1783. Another store was soon opened at St. Marks with headquarters in Pensacola. Other offices were at St. Augustine, Florida, and Edinburgh, Scotland.

Trading in furs and produce in exchange for credit or supplies, this firm became important to Spanish Indian policy. William Augustus Bowles, a bohemian Loyalist and soldier of fortune who had lived among the Creeks, was sent into Florida in 1788 to make contact with McGillivray in an effort to break the monopoly of Panton, Leslie and Company in the Creek trade on behalf of the trading house of Miller, Bonnamy and Company and their associate, John Murray, British Governor of the Bahamas.

Concerned that the Spanish, through Panton, Leslie and Company, would no longer supply him with arms and ammunition, McGillivray received Bowles. Bowles succeeded in attacking the store of Panton, Leslie and Company at St. Marks on his second try, and the alarmed Spanish continued to supply McGillivray through Panton, Leslie and Company. Spain also paid Panton, Leslie and Company for the damage done to their store by granting land.

These land claims, later known as the Forbes Putchase, were recognized as legal by the Supreme Court of the United States in 1835 and included the site of the future town of Apalachicola. Bowles was captured by the Spanish but escaped in Sierra Leone while being transported to Spain from the Phillipines.

He made his way to London and again gained support for his adventures in Florida. In 1799, he was shipwrecked on the east end of St. George Island. He made his way to the Ochlockonee River and moved inland to organize the State of Muskogee. This State defied both Spain and the United States.

A Spanish force destroyed the camp, and Bowles once again captured St. Marks. Benjamin Hawkins, the Indian Agent for the United States, succeeded in capturing Bowles in 1803. William Bowles died three years later in a Spanish prison. Panton, Leslie and Company sought and received compensation for losses sustained in defending Spanish territory and in payment of the debt owed to it by the Creeks through grants of land from the Creeks. In return, Panton, Leslie and Company, which had been reorganized as John Forbes and Company, agreed to open a store at Prospect Bluffs, eighteen miles up the Apalachicola River at what is now Fort Gadsden.

The Lower Creeks later granted the firm Forbes Island opposite Prospect Bluffs as payment for some more bad accounts. In all, the lands granted to the firm came to 1,200,000 acres.