It’s not clear if the deal was 400-hogs or “the whole right & property of the Islands Woahoo (O‘ahu) & Atooi (Kauai.)”
Whatever the agreement, Kalanikūpule was able to overcome attacks by Kā’eo and held O‘ahu (which he later lost to Kamehameha.)
Let’s look back …
In 1791, Kahekili, King of Oahu, Molokai and Maui, was on Maui with his brother Kāʻeokūlani (Kā‘eo,) King of Kauai, preparing to resist the threatened invasion of Maui by Kamehameha of Hawai‘i. (Cartwright)
Kahekili agreed with Kā’eo that after his death Kā’eo was to be regent of Maui and Molokai while Kalanikūpule, the son and heir of Kahekili, was to be King of Maui, Molokai, and Oahu, but was to reside on O‘ahu and allow Kā’eo to govern Maui and Molokai for him.
Fast forward to 1793 and Captain Brown … he was a British trader, “one of that numerous group of commercial adventurers who flocked into the north Pacific Ocean in the wake of Cook, drawn thither by the chance discovery, as one result of the last expedition led by that great navigator, of the possibilities of wealth in the fur trade between China and the coast of America.” (Kuykendall)
Brown’s three-vessel trading squadron included the ‘Butterworth’ (under Captain Brown,) ‘Prince Lee Boo’ (under Captain Sharp) and the ‘Jackal’ (under the command of Captain Alexander Stewart.)
At Maui Captain Brown seems to have entered into some sort of a politico-commercial agreement with Kahekili. Brown “had left the Isld, only a fortnight before we arrived had given them a number of Muskets, a very large quantity of Powder, and two pieces of Cannon (4 pounders)”. (Boit)
However, for these weapons, Boit says that Kahekili had “given to him the whole right & property of the Islands Woahoo (O‘ahu) & Atooi (Kauai)”. Later, Kamakau notes Kalanikūpule bargained for Brown’s assistance for “four hundred hogs”.
In July 1794, Kahekili died and, according to the prior arrangement, Kalanikūpule took control of O‘ahu and Kā‘eo ruled over Maui and Kauai.
Kā‘eo, who was residing on Maui, decided to return to Kauai. On the way he stopped with a considerable force on the northeast coast of O‘ahu, across the mountains from Waikiki, the capitol of the island.
Some fighting took place between his followers and those of Kalanikūpule, but this trouble was settled by a personal conference between the two chiefs, and Kaeo continued on around the island to Waianae, the usual point of departure for Kauai.
While resting here Kā‘eo learned of a plot among his warriors directed against himself. In this emergency he resorted to a measure not infrequently used by more civilized generals. He proposed an immediate attack on Kalanikūpule and the conquest of O‘ahu.
The plot collapsed and his followers rallied about him with enthusiasm, augmented in numbers by several bands of disaffected Oahuans. The advance toward Waikiki was begun at once and within a few days the two armies were in contact west of Honolulu. (Kuykendall)
Kalanikūpule at once engaged Captain Brown to aid him in this war (in return for four hundred hogs.) A battle was fought on the plains of Puʻunahawele in which some foreigners were killed by Mare Amara. Kalanikūpule was forced to retreat. Six days later, another battle was fought in which Kāʻeo was again victorious.
On December 12, 1794, a great battle was fought; Kalanikūpule himself with the main army held the middle ground between ʻAiea and the taro patches; Captain Brown’s men were in boats guarding the shoreline.
Thus surrounded, Kāʻeo with six of his men escaped into a ravine below ʻAiea and might have disappeared there had not the red of his feather cloak been seen from the boats at sea and their shots drawn the attention of those on land. Hemmed in from above, Kāʻeo was killed. (Kamakau)
After the victory of Kalanikūpule, a victory won by the aid of Captain Brown (and possibly also by the aid of Captain Kendrick (who was also at Honolulu on the Lady Washington,)) a salute was fired from the ships in the harbor.
One of the saluting guns on the Jackal was, through an oversight, loaded with round and grape shot, and this shot passed through the Lady Washington, killing Captain Kendrick and several of his crew.
The body of Kendrick was taken on shore for burial and the natives, who had never seen anything of the kind before, thought the prayer and burial service were “an act of sorcery to procure the death of Captain Brown.” (Kuykendall)
Toward the end of December a plot was formed among the natives for the seizure of the two vessels (Jackal and Prince Lee Boo.) On the first day of January, 1795, the plan was put into execution.
A large number of hogs having been brought to the shore for the ships, the English sailors were employed on the beach salting the pork and preparing it for shipment. Several of the crew with an officer had been sent for salt to a place some distance away.
The Englishmen being thus scattered and the vessels almost deserted, except for the two captains, who remained on board.
“Capt. Brown was walking the poop, by himself, when one of ye Savages gets up on the poop, & made a pass at the Good old Captain with an Iron dagger, which he fend’d of, & seizd a Swivell worm & drove the fellow of, he was soon followed by a number more which the captain likewise beat of …”
“… but at last he was overpower’d by numbers, & receiv’d a fatal stab in the back of the neck and was pitch’d from the poop on to the main deck where he soon expir’d, & so by there savage artfulness they got possession of both Vessells without the loss of a man on there side, in the mean time they had seiz’d the Boats & People that where on shore”. (Boit; Kuykendall)
Being in possession of the two ships, with a large quantity of arms and ammunition, Kalanikupule and his advisers conceived this to be an opportune moment for striking a decisive blow at Kamehameha.
The surviving members of the crews were compelled, under guard, to fit the vessels for sea, and when all was ready the king and his chiefs went on board and the ships were warped out of Fairhaven harbor and anchored in Waikiki bay.
The next day Mr. Bonallack, mate of the Prince Lee Boo, and Mr. Lamport, mate of the Jackal, agreed upon a plan for retaking the vessels that night. It was a desperate venture but the attempt was entirely successful, the natives on board being killed or driven off, with the exception of the king, queen, and three or four of their personal attendants.
The ships immediately put to sea, but at daybreak they again came near the shore and, after placing the king and queen in a canoe with one attendant, made all sail for the island of Hawaii, and from there, after procuring supplies, took their departure for Canton.
Within less than five months after the death of Captain Brown, Kamehameha over-ran Maui and Molokai, defeated Kalanikūpule in the great battle of Nuʻuanu, and became ruler of all the islands except Kauai. (Kuykendall)