In 1941, New Orleans architect Nathaniel C. Curtis, Sr. (1881-1953) addressed the topic of urban planning & civil defense:
"The city planner is now confronted with a situation unforeseen through the centuries. The fighting airplane has come upon the scene. By night or day, in clear air or fog, it can search out or be directed over focal concentrations of population, over places where man works and where he stores his goods, and on these dump its cargoes of death and destruction. The more concentrated the objectives become the better the chances of making a hit and the more wholesale the destruction. Moreover, in a time of war most of the factories of a warring nation are turned over to the production of war equipment and munitions, and it becomes a part of the military defense system to safeguard these against disruption or demolition, while bomb-proof shelters must be provided for all the workers in the plant.
Modern warfare requires the regimentation of large numbers of the population. All the people are ultimately concerned, civilian as well as military, and no one's safety is guaranteed.
Of all the means for carrying on offensive warfare that human ingenuity has devised, the airplane is by far the most potent, and it is no exaggeration to say that without airplanes there could hardly be a reason for any radical changes in city planning such as will be put into effect. There is no effective way so far developed to defend cities or other objectives of a widespread nature against airplanes and their destructive charges except by the employment of more airplanes. The only other way to neutralize or minimize the power of the airplane is to scatter and make less the value of its objectives."
Curtis was particularly concerned with New Orleans' vulnerability, should its pumping stations be destroyed and its air-raid shelters inundated with water:
"Would the Charity Hospital continue to function? It would as long as doctors and nurses could hold out and the essential services could be maintained. A building like the Charity Hospital cannot be destroyed except under repeated bombings. A few upper floors would be demolished--all glass windows would be shattered, but otherwise the interior would remain intact."
Read more of his address in The Tulanian (April 1941): pp. 11-12, 14. Available from Tulane University Archives.