From his base at Pontianak, Burn had helped to survey a route for the large invasion fleet to Java via the Karimata Islands
. Despite uncertainty about the direction of the winds, this route was much shorter than the alternative route around northern Borneo that had been thought to be safer.
Broek (1962) suggested that "Hermata" might have been a misreading of "Karimata," as in the Karimata islands
that were said to appear as "aimata" or "aymata" on some earlier Portuguese maps.
Soon after writing to Raffles, Burn gave assistance in surveying a route via the Karimata Islands off West Borneo for the planned assault on Java.
On the way it ran aground on a shoal off the Karimata islands, but was refloated with very little damage (PG 1/35:25 Oct 1806).
The attack--like its unsuccessful predecessor in late 1812--was prompted by a series of piratical raids, including the plundering and burning in 1812 of a British trading vessel, the Coromandel, that had become stranded on a reef in the Karimata Islands. "The enormities of Pangeran Annam have out-heroded Herod; these are too recent to require recapitulation.
Early in September, a British store-ship, attacked in the Karimata straits by a ship and several prahu under the command of Pangeran Anom, brought the news that the Coromandel had gone aground on a reef in the Karimata Islands early in August, and was falling apart.