Editing Operation Sea Lion (section)

== Army ==

=== Panzers ashore ===
Providing armour support for the initial wave of assault troops was a critical concern for Sea Lion planners, and much effort was devoted to finding practical ways of rapidly getting tanks onto the invasion beaches in support of the first echelon. Though the Type A barges could disembark several medium tanks onto an open beach, this could be accomplished only once the tide had fallen further and the barges were firmly grounded along their full length; otherwise, a leading tank might topple off an unsteady ramp and block those behind from deployment. The time needed for assembling the external ramps also meant that both the tanks and the ramp assembly crews would be exposed to close-quarter enemy fire for a considerable time. A safer and faster method was needed, and the Germans eventually settled on providing some tanks with floats and making others fully submersible.  It was nevertheless recognised that a high proportion of these specialised tanks might be expected not to make it off the beach.

==== ''Schwimmpanzer'' ====
The ''Schwimmpanzer'' II Panzer II, at 8.9 tons, was light enough to float with the attachment of long rectangular buoyancy boxes on each side of the tank's hull. The boxes were machined from aluminium stock and filled with Kapok sacks for added buoyancy. Motive power came from the tank's own tracks which were connected by rods to a propeller shaft running through each float. The ''Schwimmpanzer'' II could make 5.7&nbsp;km/h in the water. An inflatable rubber hose around the turret ring created a waterproof seal between the hull and turret. The tank's 2&nbsp;cm gun and coaxial machinegun were kept operational and could be fired while the tank was still making its way ashore. Because of the great width of the pontoons, ''Schwimmpanzer'' IIs were to be deployed from specially-modified Type C landing barges, from which they could be launched directly into open water from a large hatch cut into the stern. The Germans converted 52 of these tanks to amphibious use prior to Sea Lion's cancellation.<ref name=Schenk113>Schenk, p. 113</ref>

==== ''Tauchpanzer'' ====
[[File:Bundesarchiv Bild 101II-MW-5674-45, Übungen mit Panzer III für Unternehmen Seelöwe.jpg|thumb|left|A [[Panzer III]] ''Tauchpanzer'' under test (1940); the [[crane ship]] {{SMS|Viper|1876|2}}, which was to support Tauchpanzer operations, is in the background]]
The ''Tauchpanzer'' or [[Deep fording|deep-wading]] tank (also referred to as the ''U-Panzer'' or ''Unterwasser Panzer'') was a standard [[Panzer III]] or [[Panzer IV]] medium tank with its hull made completely waterproof by sealing all sighting ports, hatches and air intakes with tape or caulk. The gap between the turret and hull was sealed with an inflatable hose while the main gun mantlet, commander's cupola and radio operator's machine gun were given special rubber coverings. Once the tank reached the shore, all covers and seals could be blown off via explosive cables, enabling normal combat operation.<ref name=Schenk111>Schenk, p. 111</ref>

Fresh air for both the crew and engine was drawn into the tank via an 18&nbsp;m long rubber hose to which a float was attached to keep one end above the water's surface. A radio antenna was also attached to the float to provide communication between the tank crew and the transport barge. The tank's engine was converted to be cooled with seawater, and the exhaust pipes were fitted with overpressure valves. Any water seeping into the tank's hull could be expelled by an internal [[bilge]] pump. Navigation underwater was accomplished using a directional [[gyrocompass]] or by following instructions radioed from the transport barge.<ref name="Schenk111" />

Experiments conducted at the end of June and early July at Schilling, near [[Wilhelmshaven]], showed that the submersible tanks functioned best when they were kept moving along the seabed as, if halted for any reason, they tended to sink into the seabed and remain stuck there. Obstacles such as underwater trenches or large rocks tended to stop the tanks in their tracks, and it was decided for this reason that they should be landed at high tide so that any mired tanks could be retrieved at low tide. Submersible tanks could operate in water up to a depth of {{convert|15|m|ft|0}}.<ref name=Schenk110-111>Schenk, pp. 110–11</ref>

The ''Kriegsmarine'' initially expected to use 50 specially-converted motor coasters to transport the submersible tanks, but testing with the coaster ''Germania'' showed this to be impractical. This was due to the ballast needed to offset the weight of the tanks, and the requirement that the coasters be grounded to prevent them from capsizing as the tanks were transferred by crane onto the vessel's wooden side ramps. These difficulties led to development of the Type B barge.<ref name="Schenk110-111" />

By the end of August the Germans had converted 160 Panzer IIIs, 42 Panzer IVs, and 52 Panzer IIs to amphibious use. This gave them a paper strength of 254 machines, about an equivalent number to those that would otherwise have been allocated to an armoured division. The tanks were divided into four battalions or detachments labelled ''Panzer-Abteilung'' A, B, C and D. They were to carry sufficient fuel and ammunition for a combat radius of 200&nbsp;km.<ref name=Evans121>Evans, p. 121</ref>

=== Specialised landing equipment ===
As part of a ''Kriegsmarine'' competition, prototypes for a prefabricated "heavy landing bridge" or [[jetty]] (similar in function to later Allied [[Mulberry Harbour]]s) were designed and built by [[Krupp]] Stahlbau and Dortmunder Union and successfully overwintered in the North Sea in 1941–42.<ref name=Bonnard>''Alderney at War''. Brian Bonnard. 1993. {{ISBN|0-7509-0343-0}}. pp. 106–08. Alan Sutton Publishing.</ref> Krupp's design won out, as it only required one day to install, as opposed to twenty-eight days for the Dortmunder Union bridge. The Krupp bridge consisted of a series of 32m-long connecting platforms, each supported on the seabed by four steel columns. The platforms could be raised or lowered by heavy-duty winches in order to accommodate the tide. The German Navy initially ordered eight complete Krupp units composed of six platforms each. This was reduced to six units by the autumn of 1941, and eventually cancelled altogether when it became apparent that Sea Lion would never take place.<ref name=Schenk139>Schenk, p. 139</ref>

In mid-1942, both the Krupp and Dortmunder prototypes were shipped to the [[Channel Islands]] and installed together off [[Alderney]], where they were used for unloading materials needed to fortify the island. Referred to as the "German jetty" by local inhabitants, they remained standing for the next thirty-six years until demolition crews finally removed them in 1978–79, a testament to their durability.<ref name=Schenk139 />

The German Army developed a portable landing bridge of its own nicknamed ''Seeschlange'' (Sea Snake). This "floating roadway"  was formed from a series of joined modules that could be towed into place to act as a temporary jetty. Moored ships could then either unload their cargo directly onto the roadbed or lower it down onto waiting vehicles via their heavy-duty booms. The ''Seeschlange'' was successfully tested by the Army Training Unit at Le Havre in France in the autumn of 1941 and later chosen for use in ''[[Operation Herkules]]'', the proposed Italo-German invasion of [[Malta]]. It was easily transportable by rail.<ref name=Schenk139 />

A specialised vehicle intended for Sea Lion was the ''[[Landwasserschlepper]]'' (LWS), an amphibious tractor under development since 1935. It was originally intended for use by Army engineers to assist with river crossings. Three of them were assigned to Tank Detachment 100 as part of the invasion; it was intended to use them for pulling ashore unpowered assault barges and towing vehicles across the beaches. They would also have been used to carry supplies directly ashore during the six hours of falling tide when the barges were grounded. This involved towing a ''[[Karl Kässbohrer Fahrzeugwerke|Kässbohrer]]'' amphibious trailer capable of transporting 10–20 tons of freight behind the LWS.<ref name=Schenk132-133>Schenk, pp. 132–33</ref> The LWS was demonstrated to General Halder on 2 August 1940 by the Reinhardt Trials Staff on the island of [[Sylt]] and, though he was critical of its high silhouette on land, he recognised the overall usefulness of the design. It was proposed to build enough tractors that one or two could be assigned to each invasion barge, but the late date and difficulties in mass-producing the vehicle prevented this.<ref name="Schenk132-133" />

=== Other equipment to be used for the first time ===

Operation Sea Lion would have been the first ever amphibious invasion by a mechanised army, and the largest amphibious invasion since [[Gallipoli campaign|Gallipoli]]. The Germans had to invent and improvise much of equipment to be used, also proposing to use some new weapons and use upgrades of their existing equipment for the first time. These included:

# New [[antitank gun]]s and [[Armor-piercing ammunition|ammunition]]. The standard German antitank gun, the 37&nbsp;mm [[Pak 36]], was capable of penetrating the armour of all 1940 British tanks except the [[Matilda II tank|Matilda]] and [[Valentine tank|Valentine]]. Armour-piercing ballistic capped (tungsten-cored) ammunition (Pzgr. 40) for 37&nbsp;mm Pak 36 had become available in time for the invasion.<ref>{{cite web
| url         = http://www.littlewars.se/sealion/germanweapons.html
| title       = German Weapons – Operation Sealion (Seelöwe) – The German Invasion of Britain 1940
| website     = littlewars.se
| access-date  = 28 April 2018
| url-status     = live
| archive-url  = https://web.archive.org/web/20180428145550/http://www.littlewars.se/sealion/germanweapons.html
| archive-date = 28 April 2018
}}</ref>{{citation needed|date=May 2013}}{{original research inline|date=May 2013}}{{unreliable source?|date=October 2014}} The 37&nbsp;mm Pzgr.40 would still have had trouble penetrating the Matilda II's armour<ref>{{cite web
| url         = http://mr-home.staff.shef.ac.uk/hobbies/ww2pen3.pdf
| title       = Ww2pen3.doc
| access-date  = 10 May 2013
| url-status     = live
| archive-url  = http://archive.wikiwix.com/cache/20170216085132/http://mr-home.staff.shef.ac.uk/hobbies/ww2pen3.pdf
| archive-date = 16 February 2017
}}</ref> so the first echelon units replaced theirs with French or Czechoslovak 47&nbsp;mm guns (which weren't much better).<ref name=Schenk183>Schenk p. 183</ref> The [[Pak 36]] began to be replaced by the 50&nbsp;mm [[Pak 38]] in mid-1940. The [[Pak 38]], which could penetrate a Matilda's armour, would probably have seen action first with Sea Lion as it would have been issued initially to the ''[[Waffen-SS]]'' and the ''Heer'''s elite units, and all those units were in the Sea Lion force.{{citation needed|date=February 2019}} These included the ''[[SS Leibstandarte Adolf Hitler]]'' regiment, the ''Großdeutschland'' regiment, 2 mountain, 2 ''Jäger'', 2 ''Fallschirmjäger'', 4 panzer, and 2 motorised divisions. In addition, the 7th Infantry division was considered one of the best in the ''Heer'', and the 35th almost as good.{{citation needed|date=February 2019}}
# Captured French armoured tractors.<ref>p. 183 Schenk</ref> The use of these tractors by the first wave units was intended to reduce their dependence upon horses and probably would have reduced the problems of getting supplies off the beaches. In addition to their proposed use on the beaches, the Germans later used them as tractors for antitank guns and munitions carriers, as self-propelled guns, and as armoured personnel carriers. There were two main types. The [[Renault UE Chenillette]] (German name: ''Infanterie Schlepper UE 630 (f)'') was a light tracked armoured carrier and prime mover produced by France between 1932 and 1940. Five to six thousand were built, and about 3,000 were captured and overhauled by the Germans.<ref>[[Anthony Tucker-Jones]], ''Hitler's Great Panzer Heist'', Pen & Sword Books, 2007, pp. 59, 155</ref> They had a storage compartment that could carry 350&nbsp;kg, pull a trailer weighing 775&nbsp;kg for a total of about 1000&nbsp;kg, and could climb a 50% slope. The armour was 5–9&nbsp;mm, enough to stop shell fragments and bullets. There was also the [[Lorraine 37L]], which was larger, of which 360 fell into German hands. In that vehicle a load of 810 kilograms could be carried, plus a 690&nbsp;kg trailer pulled for a total of 1.5 tonnes. The use of such captured equipment meant that the first wave divisions were largely motorised,<ref name=Schenk183 /> with the first wave using 9.3% (4,200) of the 45,000 horses normally required.<ref>Peter Fleming says on page 229 that the number of horses was reduced to 4,200 for the first wave (466 per division) and 7,000 for the second wave.</ref>
# 48× [[Stug III]] Ausf B Assault Guns – 7.5&nbsp;cm StuK 37 L/24, 50&nbsp;mm armour and improved suspension. Some were to be landed with the first wave.<ref>p. 185 Schenk</ref>
# [[Panzer III]] F/G upgraded with more armour on the mantlet and progressively from 3.7&nbsp;cm KwK 36 L/46.5 to 5&nbsp;cm KwK 38 L/42.{{citation needed|date=May 2013}}
# 72 ''[[Nebelwerfer]]'', to be landed with the second and third waves.<ref name="p. 184 Schenk">p. 184 Schenk</ref>
# 36× ''[[Flammpanzer II]]'' [[flamethrower tank]]s, 20 to land with the first wave.<ref name="p. 184 Schenk" />
# 4 or more [[7.5 cm Leichtgeschütz 40|75 mm ''Leichtgeschütz'' 40]] recoilless guns, for use by paratroopers. The LG 40 could be split into four parts with each part being dropped on a single parachute.<ref>"M M Evans, Invasion!: Operation Sea Lion, 1940, p. 181; "German Airborne Troops" by Roger Edwards (1974) p. 32"</ref>