The airship is really taking a beating in this thread. 10% chance to spontaneously crash? Vulnerable to being shot down by riflemen?
Airships are tougher and more resilient than most of you seem to be giving them credit for. WWI zeps had a relatively tough outer skin, multiple non-connected gasbags, defensive machine guns, and the ability to flee to altitudes beyond the reach of any contemporary airplane. A couple of biplanes taking on a zep wasn't that cut-and-dried of a procedure until the Allies started fitting their planes out with Pomeroy explosive bullets that were capable of piercing the outer skin, rupturing a gasbag, and igniting the escaping hydrogen gas. If your Civ happens to have access to helium, which the Germans did not, even this tactic wouldn't have been nearly as effective.
2. I have found no record of Zepplins ever being used in tactical role against either land or sea targets, much less any basis for their ridiculous X2strength against naval units. They were sometimes used in a naval recon role, but even then they were only effective insofar as they had the ability to direct surface ships to the target (radio again).
Airships were the only real weapon the Allies had against the U-boats up until the invention of radar. The year that airship escorts began in earnest, the number of merchant ships sunk by U-boats along the Atlantic seaboard dropped from nearly 500 to 64. No ship escorted by an airship was ever sunk, and only one airship was lost in combat with a U-boat when its engines failed and the U-boat's deck gunner finally managed to puncture enough gasbags for the airship to lose buoyancy and crash.
The airships were capable of calling in support from Catalina bomber squadrons and surface ships, but they were armed with depth charges and were generally capable of taking care of business themselves.
If anyone's interested in reading more, check out the book
Blimps & U-boats : U.S. Navy airships in the battle of the Atlantic by J Gordon Vaeth.
The point is, airships were not abandoned because they were slow, lumbering deathtraps which could be destroyed by a bored rifleman. They were simply outclassed by fixed-wing aircraft as power-to-weight ratios started to improve. And as technological history has shown, no innovation is guaranteed to follow another. Lighter-than-air flight is relatively simple and based upon extremely basic principals of physics. Heavier-than-air flight is counterintuitive, difficult, and was widely denounced as a crackpot's dream up until the day the Wright brothers did their thing. Given time for refinement and experimentation without the pressure of fixed-wing aircraft, the airship fleets could have become extraordinarily effective against ground and naval forces.
And in a game where the Zulus regularly mount tank invasions of an isolated and technologically backwards England, historical plausibility must always take precedence over historical accuracy.