well, in that case you do not have any clue about Cossacks.
not only they were superb light cavalry, they were also good quality fearless infantrymen, who learned how ride a horse and how to handle weapons since the time they can walk...
even 19 century battlefield was very fit to role of cossacks. the Donskie Cossacs (26 regiments) alone just in a half of year 1812 killed over 18,000 Frenchmen, captured prisoner 10 French generals, 1,047 French officers and 40,000 soldiers. They also captured 15 French flags, 364 artillery pieces, 1,066 ammo boxes.
besides, it was a cossack bullet that stroke Swedish king Charles XII in the foot during Poltava siege

.
smells like BS. even take Poltava battle. Swedes invaded Ukraine with 32,000 troops and laid siege to Poltava. after numerous inconclusive skirmishes, in the final assault, Charles ordered his army forward in the classic pattern of attack, sending 18,000 Swedes against 44,000 well-entrenched Russians, with drums beating and bayonets fixed. this brought about his defeat quickly as the Russians massacred his advancing troops and overrrun the rest with cavalry. Swedes lost almost 7,000 men, the losses of Peter the Great were less than 1,400...
I am not sure how to rate these superior Swedish elite fighting skills and/or tactics - bravery or stupidity?
you are merely referring to the fact that Russians lost at Narva (honestly, no wonder - at that time Swedes had the best soldiers in Europe). Czar Peter the Great, embarassed by such a crushing defeat, shortly reorganized his men along the lines of European armies, adopting their warfare tactics, and he began to win one battle after another...
want to line up 12,000 Swedes vs Peter's own lifeguard - Preobrazhensky and Semonovsky elite regiments (who didnt even blink an eye during Narva) ??? - make my day

.