The use of “lighter than air” vehicles (balloons) used for military purposes was not a new idea. Indeed, since first attempted as “Observation Craft” by France in the 18th Century, the theory of their use as a war weapon was exploited by just about every major Power. With a workable model (to be used for improving transportation of material and passengers) – was first developed by Ferdinand Zeppelin (1900), Imperial Germany quickly began to develop “war models”. Not to be undone, Great Britain and The United States both began to see their worth and began to develop “Airships” - to be attached to each Countries Air Corps.
The theory of the vehicle, which used a lighter than air source (gas) to raise and keep aloft the vehicle – it was The US that only used Helium (while all other Nations employed Hydrogen). A balsa wood/light steel frame work was covered in silk or reinforced fabric. A series of heating “blowers” (positioned throughout the vessels structure), maintained the gases stability. Originally, models used small specially designed Aeroplanes to power and create forward momentum. By the start of World War I, separate propeller units were used for lift (and to assist in descent).
A common problem with Airships was defense. Capable of destruction by specially designed “Balloon Buster” Aircraft, the fell prey to machine gun strikes and artillery rounds (air bursts). This required Airships to operate ever higher (and thus lessened their initial role as Bombing Platforms). Germany and England deployed the most Airships in World War I (the US did not deploy them in actual combat, but used them at Sea in conjunction with Observation duties with The Navy and Air Corps). Most Airships by 1917 had some form of “self-defense” measures (Machine Gun mounts, mostly). There were 4 principle Classifications of these vessels: Airship, Aerostat, Drigible, Blimp (the term “Zeppelin” is not a classification but a manufacturing Brand name).
These classes were broken down into 3 further Sub-Classes. They were: Rigid, Non-Rigid and Semi-Rigid. These classes identified the construction type of ship. They also identified “Air” from “Gas” usage. By the end of War War I, most Countries began to concentrate of developing new and better Aircraft. However, The United States and England continued on developing The Airship as a viable military Observation vessel. Although most programs disappeared with the advent of The Jet, Observation and Cargo Airships are still very much in use and development by many World Powers.