Beyond that, there's the minor point the people who
did you look at a maritime chart? Those are substantially different than google maps in that they show water depth, known obstacles, sand banks etc. While there will be some differences in a current one compared to 1861, the general topography of the river and said obstacles will be very similar
Beyond that, there's the
minor point the people who maintain the aids to navigation (bouys, lighthouses, dredged channels, etc.) ALL work for the United States.
And as far as the defenses of Delaware Bay go, it's worth looking at some actual sources.
The Department of Pennsylvania was created as a military department (in other words, a theater-level command) on April 27, 1861, with headquarters (variously) at Baltimore and then Philadelphia; the initial commanding general was Major General (PA) Robert Patterson; he was relieved by Major General John A. Dix in 1861; the department as such was disestablished in 1862 and then re-established in 1864; in the interim, however, Pennsylvania was split into smaller commands, namely at Philadelphia (Delaware Bay) and, at times, southeastern (Department of the Susquehanna) and southwestern (Department of the Monanghela).
After Dix, the troops in the state (regulars, USVs, and militia) were (variously) commanded by generals George Cadwalader and John F. Reynolds. On December 31, 1861, active duty strength in Pennsylvania was listed at 5,200 (not including militia).
Forts Mifflin and Delaware were garrisoned in April, 1861 (Delaware initially with a 50-man regular battery), and the regulars were reinforced throughout the war by a mix of long-service US Volunteers (400 men by April, 1862, regulars and USVs) and both Delaware and Pennsylvania militia, as well as militia units federalized from other states as short-service; the Ten Gun Battery and supporting works were built to support Fort Delaware as well. By March, 1862, the garrison included 47 RA, and a battalion of four batteries of USV (PA) artillery (including both heavy – 1st Pennsylvania Marine and Fortification Artillery - and light artillerymen, under Lt. Col. Delavan D. Perkins, a regular, manning 53 guns, rising to 76 guns by February, 1863; later 3rd Pennsylvania Heavy Artillery) to an aggregate of ~400 to ~750; battery commanders included captains Stanislaw Mlotkowski, John J. Young, John J. Stevenson, and Franz von Schilling; added a battalion of Delaware USV infantry (detached from 5th Delaware, Col. Henry S. McComb) that brought the garrison up to ~900 and then ~1,200 in 1863.
Officers assigned to command the works and improve them during the war included Perkins, Robert C. Buchanan, Albin Schoepf, and Daniel Tyler, among others. Here's Perkins' entry in in
Cullum:
Delavan D. Perkins
Military History. — Cadet at the Military Academy, July 1, 1845, to July 1, 1849, when he was graduated and promoted in the Army to Bvt. Second Lieut., 2d Artillery, July 1, 1849.
Served: in garrison at Ft. Monroe, Va., 1849‑50; at the Military (Second Lieut., 4th Artillery, Mar. 31, 1850) Academy, as Asst. Professor of Mathematics, Sep. 1, 1850, to Apr. 1, (First Lieut., 4th Artillery, May 27, 1854) 1856; in garrison at Ft. Hamilton, N. Y., 1856; in Florida Hostilities against the Seminole Indians, 1856‑57; on frontier duty at Ft. Leavenworth, Kan., 1857, 1858, in quelling Kansas disturbances, — on Utah Expedition, 1858‑60, being engaged with Hostile Indians in Kirby Valley in Skirmishes, Aug. 11 and Sep. 6, 1860; on leave of absence, 1860‑61; and in garrison at Ft. Washington, Md., 1861.
Served during the Rebellion of the Seceding States, 1861‑65: in
(Captain, 16th Infantry, May 14, 1861: Declined)
(Captain, 4th Artillery, May 17, 1861)
Operations on Upper Potomac, and in Shenandoah Valley, June 7, 1861,
(Major, Staff — Additional Aide-de‑Camp, Nov. 18, 1861) to Nov. 21, 1862; Asst. Inspector of 12th Army Corps, with the rank of Lieut.‑Colonel, Aug. 20, 1862, to Apr. 11, 1863; in command of Ft. Delaware, and in charge of Prisoners of War confined there, Nov. 21, 1862, to Mar. 16, 1863; as Assistant to the Provost Marshal of the State of Connecticut, Apr. 25, 1863, to July 7, 1864; and as Assistant in the (Major, Staff — Asst. Adjutant-General, June 1, 1864) Adjutant-General's Office at Washington, D. C., July 7, 1864, to Jan. 6, 1865. Died, Jan. 6, 1865, at Washington, D. C.: Aged 38.
Not exactly a slouch; USMA, artillery specialist, active service in the field, assigned to mutiple harbor defense posts, professor of mathematics at USMA, line and staff duties, and only 38 in 1865, so he's 35 or so in 1862. Presumably he can do as well as George Armistead did at Fort McHenry in 1814.
The Philadelphia Navy Yard PNY had a guard ship assigned immediately in 1861 (the side-wheel gunboat USS
Princeton was the first) and guardboats (generally armed steam tugs, revenue cutters, etc.) attached to the Navy Yard were routinely assigned to the fort and lower bay for picket duty. At least two such vessels were assigned at any one time during the course of the war. PNY’s commandants during the war included Samuel F. Du Pont and C.K. Stribling, among others; also, not exactly slouches.
Sources for all of the above are the
Official Records, as presented for free and searchable by Cornell, here:
http://ebooks.library.cornell.edu/m/moawar/index.html
Nice summary of the troops stationed at Fort Delaware historically during the war (obviously, not a conflict where there was much of a maritime threat, so that woud change in the event of a threat of European intervention); even so, worth noting are the numbers of regulars on station:
http://www.fortdelaware.org/union%20units.htm
Entirely separate from the United States Volunteers raised in Pennsylvania in 1861-65 (and for that matter, the Pennsylvania Reserve Division organized under state authority in 1861 but transferred to the US for active service, or the USCT units raised in Pennsylvania from 1863 onwards) the state of Pennsylvania routinely raised state militia units, for state and at time, federal service, during the war as well. Philadelphia, because of the size, wealth, and age of the city, had a long militia tradition which included the maintenance of some seven regiments of infantry and artillery, which formed a nominal state militia division in the city (and, obviously, capable of being deployed into the field in southeastern Pennsylvania, southern New Jersey, and/or Maryland, as necessary).
Philadelphia in the Civil War, by Frank H. Taylor, goes into a significant amount of detail, and is available on-line for free:
https://archive.org/details/cu31924028861842
The two largest such mobilizations were in 1862 and 1863, respectively, in response to the Maryland and Gettysburg campaigns. The 1862 mobilization, ordered initially by Gov. Curtin, certainly provides an example of what the state could do, essentially under its own authority and largely its own resources, early in the war.
http://www.pa-roots.com/pacw/1862militia/index.html
It is worth noting that with roughly ten days’ notice in September, 1862
, a force of some 40,000 men were organized and in the field, with 25,000 in the southeastern part of the state of Pennsylvania, and another 15,000 in the southwestern part. These troops were organized into 25 regiments of infantry, two separate battalions and 27 companies of infantry, five companies (batteries) of artillery, and 12 companies (troops) of cavalry.
So, presumably in the event of the balloon going up in the winter of 1861-62, along with whatever elements of the USN and USRCS, and US regular/USV force of some 527,000, that Washington might decide to detach to defend the nation's second largest city and largest shipbuilding center, there's the minor point that:
a) there's a functioning military headquarters/theater command, and with existing fixed defenses with an active garrison (and this, historically, was a secondary theater in the conflict that was fought), and with arsenals and armories within the region to be defended;
b) there's a functioning naval inshore defense headquarters command, and within shipyards and a shore establishment within the region to be defended;
c) there's a functioning Pennsylvania STATE level military headquarters and command structure that, historically, maintained several thousand 1st line reserves in the region (which presumably would train as heavy artillery, rather than infantry, in the event of a maritime threat)
and and was able to mobilize some 25,000 1st and 2nd lines reserves in 1862 when actually tested (and one can, presumably, add Delaware and New Jersey's state-level resources to the mix).
And, of course, Philadelphia (and by extension, Wilmington, Chester, and Camden, much less Eleutherian Mills
) are nicely connected by railroad, canals, telegraphs, and all the other C3I elements of an industrial region in the mid-Nineteenth Century.
Minor elements, of course, but the examples of Baltimore in 1814 and/or Petropavlovsk in 1854, Taganrog in 1855, and the Taku Forts in 1859 all come to mind.
Best,