Editing Battle of the Atlantic (section)

==Operation Drumbeat (January–June 1942)==
{{Main|Second Happy Time}}
[[File:Allied tanker torpedoed.jpg|thumb|Allied tanker ''[[SS Dixie Arrow|Dixie Arrow]]'', torpedoed by {{GS|U-71|1940|2}}, in 1942]]
[[File:Casablanca convoy.jpg|thumb|An Allied [[convoy]] heads eastward across the Atlantic, bound for Casablanca, in November 1942]]

The [[attack on Pearl Harbor]] and the subsequent German declaration of war on the United States had an immediate effect on the campaign. Dönitz planned to attack shipping off the [[East Coast of the United States|American East Coast]]. He had only five [[Type IX U-boat|Type IX]] boats able to reach US waters for [[Second happy time|Operation Drumbeat]] (''Paukenschlag''), sometimes called by the Germans the "second happy time."

The US, having no direct experience of modern naval war on its own shores, did not employ a blackout. U-boats stood off shore at night and picked out ships silhouetted against city lights. Admiral [[Ernest King]], Commander-in-Chief United States Fleet (Cominch), who disliked the British, initially rejected Royal Navy calls for a coastal blackout  or convoy system. King has been criticised for this decision, but his defenders argue the United States destroyer fleet was limited (partly because of the sale of 50 old destroyers to Britain earlier in the war), and King claimed it was far more important that destroyers protect Allied troop transports than merchant shipping.<ref>{{Cite book |last=Wragg |first=David |title=9781844685424 |publisher=Pen & Sword Books |year=2009}}</ref><ref>{{Cite book |last=Moses |first=Sam |title=At All Costs: How a Crippled Ship and Two American Merchant Mariners Turned the Tide of World War II |date=4 September 2007 |publisher=Random House}}</ref> His ships were also busy convoying [[Lend-Lease]] material to the [[Soviet Union]], as well as fighting the Japanese in the Pacific. King could not require coastal blackouts—the Army had legal authority over all civil defence— and did not follow advice the Royal Navy (or Royal Canadian Navy) provided that even unescorted convoys would be safer than merchants sailing individually. No troop transports were lost, but merchant ships sailing in US waters were left exposed and suffered accordingly. Britain eventually had to build coastal escorts and provide them to the US in a "reverse Lend Lease", since King was unable (or unwilling) to make any provision himself.{{sfn|Costello|Hughes|1977|p=196}}

The first U-boats reached US waters on 13 January 1942. By the time they withdrew on 6 February, they had sunk 156,939&nbsp;tonnes of shipping without loss. The first batch of Type IXs was followed by more Type IXs and Type VIIs supported by [[Type XIV U-boat|Type XIV]] "Milk Cow"{{sfn|Costello|Hughes|1977|p=203}} tankers which provided refuelling at sea. They sank 397 ships totalling over 2&nbsp;million tons. In 1943, the United States launched over 11&nbsp;million tons of merchant shipping; that number declined in the later war years, as priorities moved elsewhere.

In May, King (by this time both Cominch and [[Chief of Naval Operations|CNO]]) finally scraped together enough ships to institute a convoy system. This quickly led to the loss of seven U-boats. The US did not have enough ships to cover all the gaps; the U-boats continued to operate freely during the [[Battle of the Caribbean]] and throughout the [[Gulf of Mexico]] (where they effectively closed several US ports) until July, when the British-loaned escorts began arriving. These included 24 anti-submarine armed trawlers. The institution of an interlocking convoy system on the American coast and in the [[Caribbean Sea]] in mid-1942 resulted in an immediate drop in attacks in those areas. As a result of the increased coastal convoy escort system, the U-boats' attention was shifted back to the Atlantic convoys. For the Allies, the situation was serious but not critical throughout much of 1942.