Glossary of Sealion Threads

In daylight, the Royal Navy would have suffered some losses. At night, very few. Plus the Navy would have fighter escorts much of the time. The Luftwaffe might have been able to drive 11 Group from the sector stations south of the Thames but not prevent the squadrons being based elsewhere and using airfields in the south to refuel and rearm.

Stukas attacking RN warships are Stukas not providing CAS to the Heer ashore. And in either role are extremely vulnerable.
But in Crete, the Lutwaffe had a different primary task and that was to support the airborne units. Most air operations were aimed at capturing the island. Attacking RN ships was a secondary objective. Furthermore, the strength of the Luftwaffe was very limited, some reasons:

1. poor airfields in the area, moreover there were few, which reduced the strength of the Luftwaffe in the area
2. lack of fuel, if the Germans had not recovered the supplies of aviation gasoline left here by the RAF, their air operations would have been further curtailed
3. unsuitable aircraft, much of the attack on RN ships was carried out by Do 17's which had a small bomb load, in addition they carried out their attacks from higher altitudes
4. poor infrastructure in Greece, which made it difficult to supply the Luftwaffe, resulting in fuel and bomb shortages
5. the long distance between the targets, which did not allow the full potential of the Ju 87 to be used, which mostly used only SC 250 bombs, only rarely were heavier ones used

All very well described in this book: (

Airfields in France would be much better supplied, closer to the operational areas, and the Luftwaffe strength would be much greater. Units equipped with the Ju 87 could use much heavier and more effective bombs than just the SC 250. British losses would certainly not be small as you claim….

1- I didn't give any indication that the losses would be "small" - in fact I specifically said that at Crete the losses were "severe". I don't think they would be small, but I don't think the LW would be able to stop the RN from largely interdicting convoys - and I don't think any reasonable modern source thinks it either.

2- I don't have the book you mentioned and can't find any information on what proportion of LW effort at the evacuation of Greece and Crete went into the naval battle versus the land one.

3- LW strength would be greater in the Channel but so would RAF strength.

4- The LW would be closer to its bases but so would the RN. At Crete the RN was operating so far from its supplies that there was a significant problem with ships running low on AA ammunition, which would not be a problem in the Channel.

I can't find an order of battle for the LW in detail, but a 1960 study states that Fliegerkorps VIII had "716 aircraft" with "514 were reported serviceable on 17 th May. They consisted of:— 228 bombers. 205 dive bombers. 114 twin engined fighters. 119 single engined fighters." As far as I can see, that's about half as many aircraft as most sources say would have been available for Sea Lion.

At Crete the RN lost three cruisers and six destroyers, plus some of the small craft of the Suda Bay base force (many of which were scuttled). That's a "sinking rate" of 0% of battleships, 0% of carriers, 27% of cruisers, 19% of destroyers, and 0% of the few small convoy escorts. If we assume that at Sealion the LW forces, being double the size, manage to sink double the percentage of British ships then they'll sink half the cruisers, leaving three; 19 destroyers, leaving 48. That's ignoring the 34 sloops and corvettes and the 165 minesweepers.

Yes, some other vessels would be damaged but given the crisis that Sealion would represent, many damaged ships would stay in the fight. At Crete there were seven destroyers damaged but most of those damaged could have kept on fighting effectively; for example HMAS Napier could still steam at 23 knots and appears to have retained full firepower; HMS Kelvin was in a similar position but reduced to 20 knots; HMAS Nizam is listed as damaged but doesn't seem to have been out of service at any time. Two of the battleships received serious damage as did some of the cruisers but there's probably a 50% chance that Revenge can stay in the fight.

When the Home Fleet came south there'd be some fraction of another five capital ships, 18 cruisers, 35 destroyers and perhaps even the two carriers. Then there'd be ships withdrawn from Western Approaches Command. So once the reinforcements arrived the RN would be stronger than before the battle, given historical loss rates.

5- In Sealion the LW also had to support the land forces just as in Crete, so there's no difference there.

6- As Finnbar points out, the RN would have suffered very little loss from the LW at night, which would allow them to range quite freely and cause havoc among convoys sitting off the English coast.

Basically, those who claim the LW would have wiped out the RN, or come close to it, are ignoring the historical evidence. We see a lot of that in forums; for example in one Sealion thread someone pointed out the sinking of Yamata, PoW and Repulse but looking at isolated incidents like that ignores the many, many actions were the air was unable to severely harm naval forces. We tend to look at the sinkings but ignore the times when nothing like that occurred, yet the sinkings are the outliers.
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It's also worth noting that in Crete many ships ended up low on AA ammunition. Working much closer to bases, RN units will be more easily supplied so this problem will be reduced (though probably not eliminated entirely). They will also be supported by the RAF and by any heavy AA near the shore, so Crete is likely a worse case than Sealion.
As for sinking the RN, the majority of initial anti-invasion fleet duties will be by the lighter forces in the immediate area. These lighter vessels are potentially more vulnerable to damage from bombing but are small targets that are not necessarily readily distinguished from invasion vessels from altitude in daytime [1]. The best chance to hit these is by strafing - which takes fighters out of fending off the RAF - or by dive bombing, using stukas which were very vulnerable without fighter protection. Level bombing would be disruptive, but is notoriously inaccurate against moving targets and is even more likely to involve misidentification of targets due to higher altitudes.
While at least some of the lighter vessels were armed trawlers etc, even these typically had at least some trained gunners on board (I can't find the reference right now as it wasn't where I thought). RN light vessels typically included light AA weapons with fully trained crews, as well as being very well equipped to attack naval and other vessels (twin 6 pounders would mince any barge, as would the 3" guns).

[1] Destroyers yes, but the other light vessels - armed trawlers, gunboats etc - would look quite similar to German vessels from a few thousand feet.
It's interesting to see that the thread with the glossary of Sealion threads is now used to redo the arguments in the Sealionthreads it refers to.