properly fortified, as lines of railway, completed or in process of construction, radiate from it to Quebec and Montreal and to Saint John and Halifax.
The harbor is one of the finest on the Atlantic Ocean, or in the world, and can easily be so fortified as to be as impregnable as Gibraltar, and far stronger than Quebec, Sebastopol, or Cherbourg.
Halifax Harbor, the great British naval depot on the American continent, now occupied by the combined fleets of England and France, closes the outlet of the great gulf lying between Cape Cod and Cape Sable, and unless Portland is defended the whole peninsula east of Lake Champlain is easily subjected to foreign control.
If Great Britain held the harbor of Portland and the line of railway to Montreal and Quebec she would drive American commerce from the ocean and the great lakes.
The strategic importance of Portland is shown by reference to any general map of the whole country, and its capabilities for defense are exhibited by the charts of the U. S. Coast Survey of 1859.
Portland Harbor is an arm of the sea, formed by five outlying islands that shut out the swell of the ocean. The main or great ship channel is only 170 rods in width, carrying from eight to ten fathoms at low water inside Bangs Island.
This island is the natural fortress that defends the approach to the harbor. Its outside shore-line, extending over one mile in a nearly straight line, rises about eighty feet above the level of the sea. The distance from this outer shore wall of the island is less than three miles from the densely populated portion of the peninsula on which the city is built.
Behind this natural fortress ships-of-war may lie deep water and shell the city, entirely protected from the guns of Fort Preble, Fort Scammel, or Fort Gorges. In point of fact, the present forts are of very little, if any, value in defending the city from guns of long range used in modern warfare.
Bangs Island contains 220 acres. By fortifying this island all possible approach to Portland by water with large ships is cut off. In that event no holding ground or place of anchorage can be found where gun-boats can reach the city without coming within range of the guns of its forts or those of Fort Gorges.
By making Bangs Island a fortress, Fort Gorges may be advantageously changed into a water battery, with only one tier of guns, and the expense of the proposed casemate battery saved, and thereby Portland would become impregnable by water.
The town itself is situated on a high peninsula, once an island, two miles and a half in length and averaging three-quarters of a mile in width, around which still sweep the tide waters of Casco Bay, approaching within a few rods from opposite sides.
A ditch of a few rods' length will change this peninsula into an island and secure a flow of the tide completely around the city. The land rises more or less abruptly on all sides from the water, reaching an elevation of 176 feet at the western end and 161 feet at the eastern end of the peninsula, so that a redoubt at each end of the city overlooking Black Bay will prevent all approach to the city. No land rises so high as that of the peninsula of Portland within ten miles. One-tenth of the expense of fortifying Sebastopol or Cherbourg would make Portland one of the strongest fortresses in the world.
As a harbor of refuge that of Portland is unrivaled, and the approach of a storm is foreshadowed by a movement of vessels in that direction.