He obtained command of a Guinea trader, and made several successful voyages, till the war with Spain broke out in January, 1762. Having saved a good round sum, he equipped a privateer, and took command of her as captain, to cruise against the French and Spaniards; but he had not been three days at sea, when his crew mutinied, and sent him that which is called in sea-phraseology a round-robin (a corruption of an old French military term, the _ruban rond_, or round ribbon), in which they wrote their names in a circle; hence none could know who was the leader.
Arming himself with his cutlass and pistols, Glass came on deck, and offered to fight, hand to hand, any man who conceived himself to be wronged in any way. But the crew, knowing his personal strength, his skill and resolution, declined the challenge. He succeeded in pacifying them by fair words; and the capture of a valuable French merchantman a few days after put them all in excellent humour. This gleam of good fortune was soon after clouded by an encounter with an enemy's frigate, which, though twice the size of his privateer, Glass resolved to engage; and for two hours they fought broadside to broadside, till another French vessel bore down on him, and he was compelled to strike his colours, after half his crew had been killed and he had received a musket-shot in the shoulder.
He remained for some time a French prisoner of war in the Antilles, where he was treated with excessive severity; but upon being exchanged, he resolved to embark the remainder of his fortune in another privateer and "have it out," as he said, with the French and Dons. But he was again taken in action, and lost everything he had in the world.
On being released a second time, he was employed by London merchants in several voyages to the West Indies, in command of ships that fought their way without convoy; and according to a statement in the _Annual Register_, he was captured no less than _seven_ times. But after various fluctuations of fortune, when the general peace took place in 1763, he found himself possessed of two thousand guineas prize-money, and the reputation of being one of the best merchant captains in the Port of London.
About that time a Company there resolved to make an attempt to form a settlement on the west coast of Africa, by founding a harbour and town midway between the Cape de Verd and the river Senegal. In the London and other papers of the day we find many statements urging the advantage of opening up the Guinea-trade; among others, a strange letter from a merchant, who tells us he was taken prisoner in a battle on that coast, and that when escaping he "crossed a forest within view of the sea, where there lay elephants' teeth in quantities sufficient to load one hundred ships."