Are all of the secret techs stand-alone? There's a case for making, say, nerve agents and gas bombardments dependent on the same tech invention event. Similarly for the various artillery-related techs.
I assume that "monoplane fighter" isn't a reference to the Fokker Eindecker of 1915, which was both the world's first fighter and the world's first monoplane fighter? Incidentally, historically the first all-metal, retractable-undercarriage monoplanes were bombers, developed in about 1932, and similar fighters didn't follow until 1935-36.
The airborne assault tech will require a prerequisite to be developed first, also a secret weapon tech: troop carrying airships. You might also want to include aircraft-carrying airships as a related secret weapn tech: these would have an active air-to-air attack rating, and a naval rating, but no troop-carrying capability.
I assume that "monoplane fighter" isn't a reference to the Fokker Eindecker of 1915, which was both the world's first fighter and the world's first monoplane fighter? Incidentally, historically the first all-metal, retractable-undercarriage monoplanes were bombers, developed in about 1932, and similar fighters didn't follow until 1935-36.
The airborne assault tech will require a prerequisite to be developed first, also a secret weapon tech: troop carrying airships. You might also want to include aircraft-carrying airships as a related secret weapn tech: these would have an active air-to-air attack rating, and a naval rating, but no troop-carrying capability.