The postponement coincided with rumours that there had been an attempt to land on British shores on or about 7 September, which had been repulsed with large German casualties. The story was later expanded to include false reports that the British had set the sea on fire using flaming oil. Both versions were widely reported in the American press and in William L. Shirer's "Berlin Diary", but both were officially denied by Britain and Germany. Author James Hayward has suggested that the whispering campaign around the "failed invasion" was a successful example of British black propaganda to bolster morale at home and in occupied Europe, and convince America that Britain was not a lost cause.