The Physics of War (21 page)

“DAMN THE TORPEDOES”

When the Confederate navy finally realized it was no match for the Union navy it decided to fight the embargo in other ways. And two of the most effective things they used were torpedoes and submarines. Indeed, the Confederates sank twenty-two Union ships and damaged twelve others using torpedoes, while losing only six ships to the Union navy in return. These “torpedoes,” however, are not what we usually think of as torpedoes, even though they were referred to by that name at the time. They were what we might call “mines” today.

Two types of torpedoes were used extensively: the spar torpedo, in which an explosive device was mounted at the end of a long spar (up to thirty feet long). It was usually mounted at the bow of an attacking vessel. When driven against an enemy ship it exploded. The only problem is that it frequently did considerable damage to the vessel carrying it. Torpedoes were also towed on long ropes or lines behind a vessel, usually at an angle of about forty-five degrees. Using
an appropriate maneuver they could also be projected at an enemy ship. And, of course, many “torpedoes” were merely set in the water. They could be detonated electrically by an operator on the shore or by some type of percussion cap.

One of the most famous battles in which torpedoes played in important role was the Battle of Mobile Bay, Alabama. It occurred in August 1864. On the Confederate side, guarding the bay was Admiral Franklin Buchanan, a veteran of numerous battles at sea. His flagship, the
Tennessee
, was an ironclad modeled after the
Virginia
. Outside the bay was Union admiral David Farragut, who had four ironclads modeled after the
Monitor
, along with several wooden ships. And he faced more than just the
Tennessee
and a few smaller ironclads. Two forts were guarding the entrance to the bay: Fort Morgan, with several large guns, and Fort Gaines. But the biggest fear for Farragut was the “torpedoes” that were floating throughout the bay. The only way through them was a narrow path directly under the guns of Fort Morgan.
¹³

Farragut planned to attack using a formation of two columns of ships. One, which would pass close to Fort Morgan, consisted of four well-protected ironclads similar to the
Monitor
. The second column consisted of four wooden warships, lashed together for safety. If one was hit, it was less likely to sink. Farragut was in the second of these, in the
Hartford
; ahead of him was the
Brooklyn
. On August 5, Farragut's armada approached the bay, and as they closed in, the guns at Fort Morgan began firing at them. The Union ships began firing back, but Farragut was not looking for an extended battle with them; he planned on rushing by them into the bay.

As the two columns approached the bay entrance, the captain of the lead ironclad, the
Tecumseh
, spotted Buchanan's
Tennessee
. It was a major danger to the column of wooden warships. But as he moved to intercept it, he forced the wooden ships into the minefield. When the captain of the
Brooklyn
saw the mines ahead he ordered his ship to stop. But directly behind him was Farragut in the
Hartford
. Annoyed, Farragut sent a message (flag message) to the captain of the
Brooklyn
to continue on. Confusion reigned, as both ships were under heavy fire. All at once an explosion rocked both ships. The lead ironclad, the
Tecumseh
, had hit a mine, and within seconds it was at the bottom of the bay.

Confusion continued, as the
Brooklyn
stopped again. It appeared as if the entire column of ships was going to collide into one another. Farragut issued an order that the line to his ship be cut, and he pulled out and began steaming past the
Brooklyn
. The captain of the
Brooklyn
yelled at him, “There are torpedoes directly ahead,” to which Farragut replied, “Damn the torpedoes…full speed ahead!” (a phrase that has become legendary). As the
Hartford
steamed ahead it struck several mines, but luck was with them. None of the mines exploded.

Meanwhile, Buchanan, who was aboard the
Tennessee
, watched in astonishment as all the Union vessels passed safely into the bay. He ordered the
Tennessee
to steam directly at the
Hartford
, which was now leading the Union ships. He planned to ram it, but the
Tennessee
was large and slow, and the
Hartford
easily eluded it as gunners from the two ships fired at one another. The
Tennessee
then made runs at several other ships, hoping to ram them, but it did little damage, so Buchanan broke off and returned to Fort Morgan.

But the fight was far from over. After inspecting his ship for damage, Buchanan ordered it out to sea again. And again the two ships—the
Hartford
(at ten knots) and the
Tennessee
(at four knots)—steamed directly toward one another. It looked like they were going to collide when, at the last moment, the
Tennessee
veered slightly. As they passed one another at point blank range, sailors on both ships fired with muskets and pistols.

Once the
Tennessee
was past the
Hartford
, however, it was surrounded by Union warships, all firing at it at the same time. And with the range being exceedingly close, they did a tremendous amount of damage. Furthermore, the gun port for one of
Tennessee
's guns jammed, and some of its other guns misfired. Then one of the incoming shells took out the
Tennessee
's steering, and it could no longer maneuver. Finally, Buchanan himself was struck by flying debris. There was nothing left for him to do but surrender, and he did.

SUBMARINES

The first submarines also saw action during the Civil War. Actually, the first submarine had been built many years before the war, in 1776 in England. It was a one-man, hand-cranked machine. And the American inventor Robert Fulton had constructed a submarine for the French navy.

As we saw earlier, the Confederates soon realized that they were badly outgunned on the surface, so much of their effort went into the region under the surface—in particular, they used submarines. In 1862 they built the first of several submarines, all of which were called “David.” (The name no doubt came from the biblical story of David challenging the giant Goliath.) It was steam driven, and, as such, it needed a smoke stack, and since both the smokestack and the breathing tube had to penetrate above the surface, it was quite limited. Its major weapon was a spar torpedo, which was mounted on the bow.
¹⁴

Within a short time Horace Hurley and two partners launched the
Pioneer
, and in 1862 they launched
Pioneer II
. By now they were experimenting with electric engines, but the only electrical engines that were being manufactured
were in the North. They attempted to smuggle some in but failed. The following year, the much larger
Hurley
was built (named for the maker). It was forty feet long and was about four feet in diameter, and it had an eight-man crew that turned a hand-cranked propeller. The hand crank was no doubt used in an effort to keep the machine as silent and undetectable as possible. The
Hurley
had a spar torpedo, and there is evidence that it was used several times in battles, and no doubt several crews died in their attempts to do so. Nevertheless, it is the only submarine that managed to sink an ironclad during the war. In 1864 it sank the Union sloop
Housatonic
. Unfortunately, it did not survive the attack and was never seen again. In 1995, however, its remnants were found off the coast of South Carolina, and it was raised in 2000. There is some evidence that it was only twenty feet away from the Housatonic when it exploded, and the concussion likely disabled it.

The Union was not very active in the production of submarines, but they made one that they called the
Intelligent Whale
, but it never saw action. Interestingly, several private ventures in both the North and the South also attempted to build submarines, but little is known about most of them. In all there may have been twenty submarines built during the Civil War, with most of them seeing no action. But the experimentation and innovation that went into them soon led to much better submarines. In particular, airlocks, compression air ballast tanks, electric motors, periscopes, and air purification systems were developed.

BALLOONS

Hot-air and hydrogen-filled balloons were used for surveillance by both the Union and Confederate armies during the war. But they were used more extensively and effectively by the Union army. In 1861 Lincoln gave orders to form a balloon corps with Thaddeus Love in command. And indeed, in several battles the information obtained using them was of considerable value. During the Seven Days Campaign of 1862, for example, Union balloons stationed seven miles from Richmond could easily observe troop movements within the city. The largest balloons (called the
Integral
and the
Union
) could carry five people and had a capacity of thirty-two thousand cubic feet. Hydrogen gas was used in most of the early balloons; it was generated from water using portable generators.
¹⁵

Almost all balloons were tethered to the ground by a long line, but they were able to climb to almost five thousand feet in the air. And although Union balloons were shot at extensively by Confederate cannons, they were generally
too high to be in range, and none were ever knocked down. Most of the larger balloons also had telegraphic equipment to transmit information to the appropriate people below.

How did these balloons work? For a balloon to rise, there has to be a force on it, and the only force readily available is a buoyant force. The Greek mathematician Archimedes was the first to understand this force, and as we saw earlier, it is now known as Archimedes principle. It states that
any body completely or partially submerged in a fluid (in this case the fluid is air) is buoyed up by a force equal to the weight of the fluid displaced by the body.

In the case of a balloon, a buoyant force (B), which is equal to weight of the air displaced, acts upward, and a gravitational force (W) acts downward. To see how this causes a balloon to rise, let's begin with the density of the gas (
) and the volume (V) of the balloon. The mass of the displaced air is going to be
V, and for its weight we need to multiply by g (the force of gravity). So the buoyant force B is
Vg. Now we need W, the weight of the balloon. For it we need the mass inside it, and this is the density of the gas inside it (D) times its volume (V), or DV, so W = DVg. The total upward force is therefore B – W =
Vg – DVg. If the upward force is positive, the balloon rises. Since hydrogen is less dense than air, the balloon will rise if filled with hydrogen (or, for that matter, any gas that is less dense than air). Also, if we heat the air inside the balloon, the molecules move farther apart and its density decreases. And again the net force is upward. This is the principle of the hot-air balloon.