"Delaware was so called, in 1703, from Delaware Bay, on which it lies, and which received its name from Lord De la War (Thomas West, with the official English title of Earl), who died onboard a vessel, while descending the bay.
The first settlement effected within the bounds of Delaware was by a number of Swedes and Finns, who arrived from Sweden in 1638, in charge was Peter Minuits, the first Governor of New York, who, after leaving the Dutch, undertook to lead a colony to America, according to a plan originally devised by the celebrated Gustavus Adolphus, King of Sweden.
On his arrival, Miinuits, with his colony, settled on Christiana Creek, near Wilmington, and there built a fort. The territory extending from Cape Henlopen to the Falls of Trenton received the name of New Sweden.
The Dutch, at New Netherlands, however, laid claim to the territory, and mutual contests subsisted for a long time between them and the Swedes. Dutch Governor Kieft, by way of keeping them in check, rebuilt Fort Nassau, about five miles south from Camden, on the eastern bank of the Delaware, which was first erected in 1623, but, being neglected, had fallen to decay. The Swedish governor, John Printz, on the other hand, by way of retaining his position and gaining the ascendancy over the Dutch, established himself at Tinicum, a few miles below Philadelphia, where he not only erected an elegant mansion for himself, but built a fort for the defense of the colony. Another fort was erected at Lewistown.
In 1651, Dutch Governor Stuyvesant built Fort Casimir, on the present site of Newcastle, five miles from Christiana. To this Printz protested; and his successor, Governor Rising, under guise of making a friendly visit to the commandant, rose upon the garrison, and, with the aid of thirty men, took possession of the fort.
Indignant at such an act of treachery, Governor Stuyvesant reported the outrage to the home government, which ordered him forthwith to bring the usurpers to submission. Accordingly, in 1655, he sailed from New York with six hundred troops, and, in a brief space of time, reduced the forts at Newcastle and Christiana, and, subsequently, all others belonging to the Swedes. Upon this, a portion of the latter, taking the oath of allegiance to Holland, remained on their estates; a few removed to Maryland and Virginia; the rest, among whom was Governor Rising, were sent to Europe.
From this time until 1664 the territory remained in possession of the Dutch; but on the conquest of New Netherlands by the English, an expedition was sent against it, under Sir Hobert Carr, to whom it surrendered, and was united to New York. In 1682, however, the Duke of York sold the town of Newcastle, and the country twelve miles around it, to William Penn, and, some time after, the territory between Newcastle and Cape Henlopen. These tracts, then known by the name of 'Territories,' constitute the present State of Delaware. Until 1703, they were governed as a part of Pennsylvania; but, at that time, they had liberty from the proprietor to form a separate and distinct assembly; the Governor of Pennsylvania, however, still exercising jurisdiction over them, until the era of the Revolution.
Source: A History of the United States, by Charles A. Goodrich, 1857