After some vague wanderings on the continent of Europe, we find him in the service of the Dutch, then at war with France. Again it may have been the Frobisher blood and a consequent predilection for the sea which made him elect to serve upon that element. He enjoyed the advantage of holding a commission under the great de Ruyter, and he fought in the Mediterranean engagement in which that famous Dutch Admiral lost his life. What he learnt under him Pitt's chronicle shows him applying in his later days when he had become the most formidable buccaneer leader on the Caribbean.

After the Peace of Nimeguen and until the beginning of 1685, when he reappears in England, little is known of his fortunes, beyond the facts that he spent two years in a Spanish prison — where we must suppose that he acquired the fluent and impeccable Castilian which afterwards served him so often and so well — and that later he was for a while in the service of France, which similarly accounts for his knowledge of the French language.

In January of 1685 we find him at last, at the age of thirty–two, settling down in Bridgewater to practice the profession for which he had been trained. But for the Monmouth Rebellion, in whose vortex he was quite innocently caught up some six months later, this might have been the end of his career as an adventurer. And but for the fact that what came to him, utterly uninvited by him, was not in its ultimate manifestation unacceptable, we should have to regard him as one of the victims of the ironical malignity of Fortune aided and abetted, as it ever is, by the stupidity and injustice of man.

In his quality as a surgeon he was summoned on the morning after the battle of Sedgmoor to the bedside of a wounded gentleman who had been out with Monmouth. The dignity of his calling did not permit him to weigh legal quibbles or consider the position in which he might place himself in the eyes of a rigid and relentless law. All that counted with him was that a human being required his medical assistance, and he went to give it.