To begin at the beginning, lets start with the visit to Macau made by the twenty two year old Alexander Dalrymple:
aboard an Indiaman in a significant year for Britain - 1759.
Dalrymple was a clerk - a "writer" in the service of the Honourable Company of Merchants Trading to the East Indies (hereinafter "The HEIC") He went on to become, first, Hydrographer to the HEIC and latterly the first Hydrographer Royal. The HEIC, from its foundation in 1601, was always interested in "bagging" convenient islands, where it could locate a trading base and some warehouses but where it could have a measure of independence from local rulers.
The late David Gledhill, Taipan of the Great and Ancient Hong, pointed out to me that a glance at the history of the British Empire shows a tendency to snap up any odd islands or defensible peninsulas which possessed deep water harbours - there are many, many examples but the ultimate HEIC one is Singapore, "bagged" by Stamford Raffles.
The Portuguese had Macau but the HEIC reckoned the Portuguese were not much of an improvement, if any, on the Qing Dynasty; they were Catholic, they were temperamental and they seemed uninterested in making the most of their opportunities.
The HEIC wanted its own place.
We now move forward to 1792. The British Government is mounting an Embassy to the Court of the Qianloong Emperor. The Embassy is to be headed by an outstanding diplomat, George Macartney:
who had already led a brilliantly sucessful mission to the court of the Empress of All the Russias, Catherine the Great. The young John Barrow, a protege of Dalrymple, who had taught himself to read and write and to speak Mandarin Chinese, is going along as interpreter.
Dalrymple, now Hydrographer Royal, asks Barrow to look out for any suitable islands with deep water anchorages.
Barrow will go on to become one of the key figures in Victorian Imperialism, suceeding Dalrymple as Hydrographer Royal and mounting a constant series
of expeditions to everywhere from Timbuctu to the Northwest Passage.
As we all know, Macartney's Embassy was not an entire sucess, but it set the terms for what happened over the next century. Macartney lands at Macau, the only permitted port of entry, and Barrow makes a note of Heung Gang*, a smallish rocky island separated from the mainland by a strait which is the perfect deep water harbour for sailing ships, as it has two entrances so you will never be windbound in it (see also The Solent...)
Heung Gang is, in fact, the only deepwater port on the coast of China not subject to silting, since a river does not flow through it (cf the East coast of the USA...)
George Macartney's observation on the Chinese Empire, on his return, deserves to be quoted at this point:
"The Empire of China is an old, crazy, first-rate Man of War, which a fortunate succession of vigilant officers have contrived to keep afloat for these hundred and fifty years past, and to overawe their neighbours merely by her bulk and appearance. But whenever an insufficient man happens to have the command on deck, adieu to the discipline and safety of the ship. She may, perhaps, not sink outright; she may drift some time as a wreck, and will then be dashed to pieces on the shore, but she can never be rebuilt on the old bottom.
"The breaking-up of the power of China (no very improbable event) would occasion a complete subversion of the commerce, not only of Asia, but a very sensible change in the other quarters of the world. The industry and the ingenuity of the Chinese would be checked and enfeebled, but they would not be annihilated. Her ports would no longer be barricaded; they would be attempted by all the adventurers of all trading nations, who would search every channel, creek, and cranny of China for a market, and for some time be the cause of much rivalry and disorder. Nevertheless, as Great Britain, from the weight of her riches and the genius and spirits of her people, is become the first political, marine, and commercial Power on the globe, it is reasonable to think that she would prove the greatest gainer by such a revolution as I have alluded to, and rise superior over every competitor."
This proved to be a completely accurate prophesy.
*Heung Gang = "Fragrant harbour"; allegedly so called because there was a joss stick factory on the island.