The German U-boat force's primary target in World War II was merchant ship, particularly those ships supplying the British Isles and the Allied war machine. Britain recognized the treat to its own survival, however, and organized defenses again the U-boats.

Here are the obstacles you will meet in accomplishing your missions:

- Silent Hunter III manual

Escorts Edit

If merchants are the primary target of your missions, escorts are your primary enemy. Their objective is, put simply, to stop you from achieving yours. They have the sensors, performance, and the weapons needed for this purpose.

As war started, few escorts were available to Britain. They were mainly assigned to convoy or task force escort duties, or to patrol the home waters and ports.

Later, however, the appearance of Hunter Killer groups changed considerably the way the war was fought. These escorts would prosecute a U-boat contact for as long as needed to destroy it, and were good at the job.

- Silent Hunter III manual

Aircraft Edit

The most effective means of fighting the U-boat was with aircraft, especially because of the way U-boat warfare worked. Virtually immobile underwater before the introduction of the snorkel, U-boats scouted the ocean for convoys on surface.

Even after initial contact, U-boats would need their surface speed to overtake the target before attack.

Capable of covering large distances quickly, airplanes would detect any U-boats approaching or trailing a convoy and, at minimum, force them underwater. Additional forces could be vectored to the location, and sometimes an attack could be made even before the sub would get to submerge.

Early in the war, patrolling aircraft would duel with a U-boat's bridge watch in visual detection. The sub was easier to spot, but more often than not the place would be detected quickly enough to allow an escape. AT night, however, the subs were safe.

With the introduction of centimetric radar, however, night could be turned into day and aircraft would appear directly over the surprised watch without warning.

Even later in the war, the strengthening of air patrols and introduction of escort carriers closed the air gap that U-boats had enjoyed in the mid-Atlantic.

- Silent Hunter III manual

Warships Edit

Encountered by U-boats as convoy escorts or as part of a task force, warships are generally not armed with any submarine armament due to their inadequate maneuverability for such tasks. On the surface, however, their direct-fire armament is devastating, and even auxiliary cruisers will deal with U-boats without much ado.
- Silent Hunter III manual

Merchants Edit

Although primarily just a target for any warship, merchant ships are not always defenseless. As the war progressed, more and more merchants bore cannons and machine guns, which even with poorly trained crews could easily pierce the pressure hull of a U-boat.

Additionally, even a small merchant may ram a U-boat if given the opportunity. The difference in mass between the two objects leaves little doubt who the loser would be.

- Silent Hunter III manual