View source for U-boat

===World War I Classes===
[[File:THE IMPERIAL GERMAN NAVY'S FLANDERS FLOTILLA DURING THE FIRST WORLD WAR Q20345.jpg|thumb|upright|Sea mines are loaded in a UC coastal submarine in the harbour of Zeebrugge]]
When the German Army captured three ports on the Belgian coast in the opening stages of the war, the German navy ordered coastal submarines to be operated from these ports against the English coast. As the war was then expected to end in a matter of months, only very small {{cvt|130|t|LT}} U-boats could be designed with an expected building time of four months. On 15 October 1914 fifteen [[Type UB I submarine|Type UB I]] U-boats were ordered, and based on that design, on 23 November a further fifteen [[Type UC I submarine|Type UC I]] coastal minelaying U-boats were ordered.{{Sfn|Rössler|2001|pp=39-44}} Given the weakness of the [[Austro-Hungarian Navy]] and the need to help their [[Turkey|Turkish]] Allies, the German Navy sent some of these U-boats to the [[Dardanelles]] and [[Black Sea]].{{sfn|Möller|Brack|2004|p=202}}

In the spring of 1915 it became clear that the war would continue well into 1916 and more coastal U-boats were ordered. The Type UB I and UC I had fulfilled the expectations but were underpowered. Thirty U-boats of the succeeding [[Type UB II submarine|Type UB II]] were ordered, which were with around {{cvt|270|t|LT}} double in size. As with the cessation of unrestricted U-boat warfare in September 1915, mine warfare became more prominent, a record number of 64 [[Type UC II submarine|Type UC II]] minelaying U-boats were ordered, which allowed for the first time for the mass-production of a U-boat. The Type UC II proved to be an ideal combination of mine and torpedo armament: on the same patrol it could lay minefields and attack shipping on the way to its target.{{Sfn|Rössler|2001|pp=50-53}}

On the resumption of the U-boat campaign in 1916, it was realized that not enough large U-boats could be built in time, and as a compromise it was decided to build an enlargened coastal U-boat capable of patrolling in the [[Western Approaches]]. The hull of the Type UC II was taken as a basis, the forward mineshaft room was replaced with a torpedo room, more powerful diesel engines provided better surface speed and larger fuel tanks extended the range. On 2 May 1916 the first twenty-four [[Type UB III submarine|Type UB III]] were ordered and as the war prolonged, more than 200 were ordered but only 96 were commissioned before the armistice.{{Sfn|Rössler|2001|pp=56-57}}{{sfn|Möller|Brack|2004|pp=46-54}} 
{| class="wikitable"
|-
|standard U-boat types
|[[German Type U 51 submarine|Type U 51]], [[German Type U 57 submarine|Type U 57]], [[German Type U 63 submarine|Type U 63]], [[German Type U 66 submarine|Type U 66]], [[Type U 81 submarine|Type U 81]], [[Type U 87 submarine|Type U 87]], [[Type U 93 submarine|Type U 93]] 
|-
|U-cruisers and merchant U-boat types
|[[German Type U 139 submarine|Type U 139]], [[German Type U 142 submarine|Type U 142]], [[German Type U 151 submarine|Type U 151]], [[German Type UD 1 submarine|Type UD 1]]
|-
|UB coastal U-boat types
|[[German Type UB I submarine|Type UB I]], [[German Type UB II submarine|Type UB II]], [[German Type UB III submarine|Type UB III]], [[German Type UF submarine|Type UF]], [[German Type UGsubmarine|Type UG]]
|-
|UC coastal minelaying U-boat types
|[[German Type UC I submarine|Type UC I]], [[German Type UC II submarine|Type UC II]], [[German Type UC III submarine|Type UC III]]
|-
|UE ocean minelaying U-boat types
|[[German Type UE I submarine|Type UE I]], [[German Type UE II submarine|Type UE II]]
|}