There were several major coastal defense construction programs:
- the “First System” (1794-1800)
- the “Second System” (1804-1812)
- the “Third System” (1816-1867)
- Post-Civil War (1870-1875)
- the “Endicott Board”, “Taft Board”, and “post-WWI” programs) (1890-1920s)
- the Harbor Defense Modernization Programs of WW2 (1940-1945).
The U.S. Army manned these defenses. After 1907, the Army's Coast Artillery Corps (C.A.C.). were responsible for these defenses.
Help using Google Maps
The Full Screen control in the upper righthand corner of the Google Maps display expands the display to cover the entire computer screen. This full-screen feature is not available on Apple IOS devices like the iPad.
You can exit out of full screen by pressing the Escape key or clicking the control in the upper righthand corner of the display.
The Map/Satellite control in the upper lefthand corner of the screen lets you choose either the normal map view or the satellite view. The satellite view allows you to see the actual military facility when you zoom in. You can choose to turn Labels on or off. The labels are the names of places, businesses, cities, etc. that appear on the map. You can turn off the labels if they obstruct your view.
When you select the Map view, you can turn on terrain features by clicking or touching the Terrain box. This will show things like mountain ranges, similar to looking at a relief map.
You can zoom in and out in a few ways. The lower righthand corner of the Google Maps display has a plus sign and a minus sign that controls zooming. If you're using a mouse with a scroll wheel, the wheel controls zooming. If you're using an IOS device like an iPhone or iPad, double-tapping the display zooms in but tapping does not zoom out.
Most touch screen devices will zoom by pinching the display with two fingers.
Wikipedia: Seacoast defense in the United States
Coastal Defense Study Group