Help who said somthing like "mine is not to question why but to do or die?

I'm pretty sure I've heard the quote you're looking for before (or something similar), but I can't find it right now..

I'll try to do some more research later this week.

The Charge Of The Light Brigade
by Alfred, Lord Tennyson

Half a league, half a league,
Half a league onward,
All in the valley of Death
Rode the six hundred.
'Forward, the Light Brigade!
Charge for the guns!' he said:
Into the valley of Death
Rode the six hundred.

'Forward, the Light Brigade!'
Was there a man dismay'd ?
Not tho' the soldier knew
Some one had blunder'd:
Their's not to make reply,
Their's not to reason why,
Their's but to do and die:
Into the valley of Death
Rode the six hundred.