"Of all the dispositions and habits which least to political
prosperity, Religion and morality are indespensable supports.
In vain would that man claim the tribute of Patriotism who should
labor to subvert these great Pilliars of human happiness."--- George Washington (Farewell Address, 19 September 1796)
"[O]ur ancestors established their system of government on morality and religious sentiment. Moral habits, they believed, cannot safely be trusted on any other foundation than religious principle, nor any government be secure which is not supported by moral habits."
-- Daniel Webster, American Jurist and Senator
"History fails to record a single precedent in which nations subject to moral decay have not passed into political and economic decline. There has been either a spiritual awakening to overcome the moral lapse, or a progressive deterioration leading to ultimate national disaster." -- General Douglas MacArthur
"No man is a good citizen unless he so acts as to show that he
actually uses the Ten Commandments, and translates the Golden
Rule into his life conduct." --Theodore Roosevelt
"Men are qualified for civil liberty in exact proportion to their disposition to put moral chains upon their own appetites--in proportion as their love of justice is above their rapacity;--in proportion as their soundness and sobriety of understanding is above their vanity and presumption;--in proportion as they are more disposed to listen to the counsels of the wise and good, in preference to the flattery of knaves. Society cannot exist, unless a controlling power upon the will and appetite is placed somewhere: and the less of it there is within, the more there must be without. It is ordained in the eternal constitution of things, that men of intemperate minds can not be free. Their passions forge their fetters."
-- Edmund Burke
“We have staked the future of all of our political institutions upon the capacity of mankind for self-government, upon the capacity of each and all of us ... to sustain ourselves according to the Ten Commandments of God.” -James Madison
Those are lovely quotes. Not really relevant, since I'm objecting to your definition of morality, not the value of moral behavior in itself, but still - nice quotes (although I might quibble with a couple of points).