The band of volunteers was under the leadership of Captain George Gibson and Lieutenant William Linn. The former, the son of a Lancaster tavern keeper, was a trapper and had gone to Pittsburgh with his brother John, where they engaged in the fur trade. In his youth he had made several voyages at sea and nearly all his life had traveled through the Indian country. William Linn was from Maryland, a farmer and skilled hunter. He had fought under Braddock and had been used as a scout along the Monongahela River.
Captain Gibson selected fifteen of the hardiest and bravest of his command. These came to be known as Gibson’s Lambs, on account of their fearlessness. Flatboats were built in Pittsburgh and the expedition started from that place Tuesday, July 16, 1776. A trip down the Ohio was extremely dangerous, as all along the river and especially the lower part, the Indians kept a constant watch.
The “Lambs” left behind them every evidence that they were soldiers. They retained rifles, tomahawks and knives, but were clad in coarse clothes resembling boatmen or traders. So clever was their disguise that even when in Pittsburgh their errand remained a secret. The impression was that they were venturing on a trading trip. The expedition successfully passed the British posts at Natchez and reached New Orleans in safety after five weeks on the water.
Louisiana was then a Spanish province, under the governorship of Don Luis de Ungaza, to whom Captain Gibson bore letters of commendation and credit, as well as to Oliver Pollock and other American merchants, then resident in New Orleans. Pollock was a wealthy Philadelphian and exercised great influence with the Spanish authorities. He assisted in negotiating for the powder. Spain was at peace with Great Britain, but willing to give secret aid to the Americans.
The British agents in New Orleans soon learned of the arrival of the Gibson party and, sensing their mission, made complaint to the Spanish authorities that rebels against the British Government were in the city.
Captain Gibson was arrested and lodged in a Spanish prison, where he was treated with the greatest consideration. While he was confined, Oliver Pollock obtained the powder and secreted it in his warehouse. The purchase amounted to 12,000 pounds and cost $1800.
The powder was divided into two portions. Three thousand pounds of it was packed in boxes, falsely marked as merchandise of various kinds, and quietly conveyed to a sailing vessel bound for Philadelphia by way of the gulf and ocean.
There was a coincidence in the fact that on the very night the ship sailed Captain Gibson “escaped” from prison, got on board the vessel and accompanied the precious powder to its destination.
The balance of the powder was turned over to Lieutenant Linn, as this was to be used on the Western frontier. This was in half casks, each containing about sixty pounds. These were smuggled during the night to the barges which were tied up in a secluded place above the city.
Lieutenant Linn hired a score of extra boatmen, mostly Americans, and on September 22, 1776, the little flotilla made a fine getaway without discovery and began its long journey up the Mississippi. The work was hard and the trip took seven months.