Does these 3 phrases all follow "как Петру I удалось"? like
не понятно, как Петру I удалось реализовать грандиозные по замыслу планы,
не понятно, как Петру I удалось поставить на дыбы страну
не понятно, как Петру I удалось за несколько лет построить столицу на болоте.

It is difficult to understand how Peter the Great succeeded in implementing his grandiose plans, succeeded in making the country stand on it's hind legs, succeeded in building Saint Petersburg on the swamp.

Quote Originally Posted by Alex80 View Post
2. "сказаться" = "to have an effect on smth / to be the cause of smth". This -ся form of "сказать" is absolutely irrelevant to the meaning of "сказать" (to say) and has no over usage except this idiomatic meaning.
"сказались в действиях" = "had an effect in (their) actions". "и" particle means "also" here.
Do you mean "no other usage except this idiomatic meaning"? I previously doubted about whether it means "... was also shown in the action".