Coastal convoys are important to England as they route the transatlantic supplies all over the nation. Most of the convoys sail without escort, relying only on the air cover provided from the mainland. Disturbing these supply lines will create a great deal of damage to the British, but mostly, will force them to provide escorts for this convoys. This will make the ocean going convoys more vulnerable with fewer escorts covering them.

The German surface fleet can engage the Atlantic convoys too if they break in. The only place through which they can break is the Denmark Strait or between Iceland and Faeroe. The British know this and have formed patrols in these areas. U-boats can be very successful against this patrols and due to their vital importance, the British will continue to replace their losses. This will affect them in other areas too as their pool of escort ships is limited. Also, there are other benefits it this objective is achieved. The German surface fleet can break into the Atlantic, the coastal waters or oceanic convoys will have less cover, while sinking highly valuable ship types, like aircraft carriers, will force the British to remove them from patrols.

With fear that the Allies may invade Norway and cut off their vital ore supplies, the Germans decided to invade first. The British will retaliate and send their “big guns” against the German invasion fleet. U-boats have a personal stake in it as Norway can provide great submarine bases, closer to the Atlantic, allowing them to spend more time on patrol against the Atlantic convoys.