used to make exquisite Niihau shell jewelry. Kāʻeokūlani was a ruler of northern Niihau who unified the island after defeating his rival, a chief named Kawaihoa. A stone wall () across a quarter of the island's southern end marked the boundaries of the two chiefs: Kāeo's land was identified by black stones and Kawaihoa's by white stones. Eventually, a great battle took place, known as Pali Kamakaui. Kāeo's two brothers from the island of Maui, Kaʻiana and his half-brother Kahekili II, the King of Maui, fought for Kāeo, and Niihau was united under his rule. Kawaihoa was banished to the south end of the island and Kāeo moved to the middle of the island to govern. Kāeo married the Queen Kamakahelei, and a future king of Niihau and Kauai named Kaumualii was born in 1790. Kauai and Niihau are said to have carried the "highest blood lines" in the Hawaiian Islands. Kamehameha managed to unify all of the islands by 1795, except for Kauai and Niihau. Two attempts to conquer those islands had failed, and Kamehameha lost many men: bodies covered the beaches on Kauai's eastern shores. Finally, in 1810, Kamehameha amassed a great fleet, and Kaumualii, the last independent , surrendered rather than risk further bloodshed. Independence again became feasible after Kamehameha's death in 1819, but was put down when Kamehameha's widow Kaʻahumanu kidnapped Kaumualii and forced him to marry her. Thereafter Niihau remained part of the unified Hawaiian Kingdom. Elizabeth McHutchison Sinclair (1800–1892) purchased Niihau and parts of Kauai from Kamehameha V in 1864 for in gold. Sinclair chose Niihau over other options, including Waikīkī and Pearl Harbor. By around 1875, Niihau's population consisted of about 350 Native Hawaiians, with 20,000 sheep. This era marked the end of the art of Hawaiian mat-weaving made famous by the people of Niihau. (Cyperus laevigatus), a native sedge, used to grow on the edges of Niihau's three intermittent lakes. The stems were harvested and used to weave (mats), considered the "finest sleeping mats in Polynesia". The mats were valued by and foreign visitors alike, but by the end of the 19th century, Hawaiians had stopped weaving due to changes in population, culture, economics, and the environment. In 1915, Sinclair's grandson Aubrey Robinson closed the island to most visitors. Even relatives of the inhabitants could visit only by special permission. Upon Aubrey's death in 1939 the island passed to his son Aylmer,