Maritime county in Ulster, washed by Lough Foyle and the Atlantic, surrounded by Donegal in the W., Tyrone in the S., and Antrim in the W., and watered by the Foyle, Roe, and Bann Rivers, somewhat hilly towards the S., is largely under pasture; the cultivated parts grow oats, potatoes, and flax; granted to the Corporation and Guilds of London in 1609, a large part of the land is still owned by them. The county town,
anufactures linen shirts, whisky, and iron goods, and does a considerable shipping trade. Its siege by the troops of James II. in 1689 is memorable.