Why and how did the US acquire American Samoa?

In the early 18th century French explorers tried to take over the islands. In the 1889 Germany invaded Samoa and (in the process) destroyed American property. The U.S then sent 3 warships to battle Germany but were met by a cyclone which wiped out most battleships on both sides. Because of this, the 2 countries came to an agreement and in 1899 the Samoan islands were divided between the U.S who took American Samoa (then known as Eastern Samoa) and Germany who took Samoa (then known as Western Samoa). The U.S expanded Pago Pago into a full naval station and secured a Deed of Cessation of Tutuila in 1900. To this day, American Samoa is known as an unincorporated territory of America, and now have their own Governor and First Lady (this came into effect in 1967). "SAMOA" on the other hand has never been acquired by the U.S and has been an "independent" nation since 1962. Independent, in that the country has its own government, Head of State and currency (American Samoa uses US dollars).