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For OTL, see https://en.wikipedia.org/wiki/Battle_of_Crete . The Germans by paratroop drops early got hold of Maleme airfield on Crete's north coast and used it to fly supplies in. An Allied attempt to quickly recover Maleme airfield was delayed a day by a sea storm (bad weather) delaying Allied landing ships, and that delay proved crucial, letting the Germans fly many more men and supplies in.
ATL :: No sea storm, and the Allied landing force attacks Maleme quickly.