Sea Lion as a planning exercise

Sea Lion can be interpreted as a planning exercise intended to persuade Hitler that the invasion could not succeed while providing cover for useful technological development. Such preparations could have value if Britain eventually lost enough naval and air strength to make a landing feasible. Even on that interpretation, an invasion in 1940, 1941 or 1942 remains unworkable with the available resources, personnel and equipment. German destroyer losses made the Channel crossing especially difficult. Moving at night would reduce some dangers while exposing the invasion to British night fighting. Darkness could also improve the chances of Lysanders carrying out the proposed mustard-gas attacks. Low, quiet approaches, potentially gliding during delivery, offered a way to disperse the gas with a better chance of survival.