Noob Question 6 - Fortifications

[Dangun]

If I play 'Road to Leningrad' as the GHC against a human opponent, when I pass Pskov around turn 5, I find a triangular mass of level 2 fortifications bordered by the Luga on one side, the Volkhow on the other, and the Gulf of Finland on the top.

How is this done?

In the same situation, playing SHC I can flood the area with units, but it doesn't appear that they build as quickly as is possible. So what am I missing? The manual isn't very helpful on this 'how to' kind of issue.

Taking a guess, it could be assigning construction battalions, swapping in better leaders, or is it building those very expensive fortified zones. Maybe I am missing something. But, if that's all there is, what is the relative effectiveness of each method? What is the priority?

[STEF78]

It represents the fortifications done on the former border of USSR before the annexion of the Baltic states in spring 1940

[Gabriel B.]

WRT AI by Rail .

his primary concern is to defend Leningrad early on, than it builds the Wolkov line .