Drogheda, a seaport town of Ireland, forming a county of itself, in the S.E. of county Louth, on the Boyne, 4 miles from the mouth of the river, and 32 miles N. of Dublin. A railway viaduct, 98 feet high, here crosses the Boyne. The river admits vessels of 500 tons, and is navigable for those of 50 tons up to Navan (19 miles). Of the population the great majority are Catholic. There are manufactures of linen, cotton, iron, and salt, and brewing and tanning are carried on. There is also a brisk export trade with Liverpool in corn, flour, cattle, butter, eggs, linen, and hides. Cromwell sacked Drogheda in 1649, and put the garrison to death.