I'm pretty sure they didn't yell "Hurray!" as they charged German MG-42s, lol
It was more likely "AHHHHH!!!" or some variant thereof
No.You wrong.
Russia really used this HURAAAA!!! before infantry assault.
The same was for romanian soldiers.
This thing have two effects.
First-persons who attack and scream loud HURAA!!! have boost for morale,because this is a word for victory,and hundreds of voices telling this really have impact for humans.It is like patriotic songs used for march,who rise the morale,and give hope where is nothing good found...but hope still exist.If the most small sign for victory will be spotted,this HURAAA!!! will be even more louder,and attackers will begin to think they really win,and will be more ferocious.
Second-This thing can frighten enemy,because if you hit them attackers hard,and kill them on mass,and they continue to swarm in waves in very aggressive and savage assault,screaming HURAAA!!! HURAAA!!!,this things begin to worry the defenders,especially when friends begin to fall and enemy kill them in the most savage way...and screaming again HURAAA!!! when they put their flag on your trench .In than moment the believe in victory begin to fall, until some soldiers will fall in panic and flee.In that moment,remaining units think if is good to stay or flee against this nuts who scram HURAAA!!! HURAAA!!!,no matter if you kill them,or if they kill you.