Even by the middle of the First World War, the threat military aircraft posed to ground forces was recognized, and adaptations of existing artillery pieces were made to fulfill the anti-aircraft artillery (AAA) role. This Signal Corps film, produced in 1935, shows the status of US Army AAA in the interwar years.
The level of sophistication in control is impressive. Predictive director control for guns ranging from 3” down to the multiple .30cal mount. Acoustic locators used to control searchlights. Of course, during World War II, radar would replace the acoustic locator. But it is important to recognize that the basic architecture behind the organization was already well thought out.
Speaking of acoustic locators, as a long range sensor, Britain built several arrays of very large “sound mirrors” for long range detection to protect the home isles from air raids in the years immediately after World War I. Their remains can still be seen in the southeast.