Sentence:  IIRC, Wells specifically described the choice of Southern England as being as much about "bridgehead" as about "decapitation strike". I think he said something about settling in to the island and building up strength before spreading out to the continent and planet.¶ That's the <WSD>Watsonian</WSD> explanation of course, the Doyleist explanation is that he was writing an allegory of white men wiping about the Tasmanians, from the point of view of the Tasmanians. He needed to set it where his English readers would be horrified by the destruction, and the Martian invasion of Korea or Florida or Sri Lanka, or even Ireland, wouldn't have had as much of an impact. 
Meaning of the word marked with <WSD> tags:  From an in-universe perspective; of or relating to an explanation within the text; internal to the narrative.