@zelda12

I have bad feelings about the book you were reading. Isn't it 'The Age of wars' ( or similar) of a swedish author, the writer who earlier wrote 'Poltava' ?
If it is this you should know that it is completely not true when it comes to Polish-Swedish wars. Actually in Poland it is a favorite example of western ignorance regarding Polish armies. Especially its description as a semi-barbaric army !!

"Was Gustav Adolphus the greatest General of the period"

I don't think so.

I am sure he was a great reformer, commander and a very brave man.
But ask yourself whom was he fighting against ?
Old fashioned imperials, Danes and Russians in the 'Time of Troubles'
( who were fighting Poles at the same time).
He was also fighting in Poland, but in this war he didn't achieved much, actually he was defeated at least one time ( and didn't take Danzig which was his another failure). The war was a success, but costly and actually Polish army was for sure his most difficult enemy.
His famous reforms were to counter this army and no other, after all !

BTW - his first victory vs. Poles ( and first Swedish victory over Poles at all !! After SEVERAL defeats.) at Walhoff in 1625 is completely biased in swedish sources i.e. they forgot that it was the Poles who were outnumbered ( and suprised) by Swedes 2 to 1, not the opposite as they claim.
Also the losses these propose are really strange.

Who was the greatest commander at that time ?

I have no idea, but if you need a commander who was almost always victorious and crushed enemies many times larger I can say that MOST OF Polish more-than-average commanders did this usually.

If you need examples, ask.

Regards Cegorach/Hetman