In his memoirs, Ismay recalled that he never solved the puzzle of how to convey his very genuine concerns of the time to the right people.[24] A thrown sticky bomb simply would not reliably stick to a vertical surface; the bomb would stick if it was thrown onto the top of a tank, where the plates were more or less horizontal – and thinner – but this reduced the throwing range to 20 yd (18 m) at the most, getting that close would only be possible in an ambush or in street fighting.[18]