21. B-25 Mitchell bomber production line at the North American Aviation plant, Inglewood, California, October 1942.
The plane’s outer wings have yet to be added, which enables the two side-by-side assembly lines to be closer together. (US Govt)
22. 243rd Infantry Division / German Imperial Army/ Western front, March 1918.
23. King George VI of Britain in London about to board a flight on 8 September 1951.