“Guerrilla warfare is used by the side which is supported by a majority but which possesses a much smaller number of arms for use in defense against oppression.”

Also quoted in "Warrior for Peace" by David Talbot, in TIME (2 July 2007), p. 50 http://www.time.com/time/specials/2007/article/0,28804,1635958_1635999_1634954-6,00.html
1961, Address at the University of Washington
Context: We increase our arms at a heavy cost, primarily to make certain that we will not have to use them. We must face up to the chance of war, if we are to maintain the peace. We must work with certain countries lacking in freedom in order to strengthen the cause of freedom. We find some who call themselves neutral who are our friends and sympathetic to us, and others who call themselves neutral who are unremittingly hostile to us. And as the most powerful defender of freedom on earth, we find ourselves unable to escape the responsibilities of freedom, and yet unable to exercise it without restraints imposed by the very freedoms we seek to protect. We cannot, as a free nation, compete with our adversaries in tactics of terror, assassination, false promises, counterfeit mobs and crises. We cannot, under the scrutiny of a free press and public, tell different stories to different audiences, foreign and domestic, friendly and hostile. We cannot abandon the slow processes of consulting with our allies to match the swift expediencies of those who merely dictate to their satellites. We can neither abandon nor control the international organization in which we now cast less than 1 percent of the vote in the General Assembly. We possess weapons of tremendous power — but they are least effective in combating the weapons most often used by freedom's foes: subversion, infiltration, guerrilla warfare, civil disorder. We send arms to other peoples — just as we send them the ideals of democracy in which we believe — but we cannot send them the will to use those arms or to abide by those ideals. And while we believe not only in the force of arms but in the force of right and reason, we have learned that reason does not always appeal to unreasonable men — that it is not always true that "a soft answer turneth away wrath" — and that right does not always make might. In short, we must face problems which do not lend themselves to easy or quick or permanent solutions. And we must face the fact that the United States is neither omnipotent or omniscient — that we are only 6 percent of the world's population — that we cannot impose our will upon the other 94 percent of mankind — that we cannot right every wrong or reverse each adversity — and that therefore there cannot be an American solution to every world problem.

Method of Guerrilla Warfare (1963)

This is also sometimes quoted as "The millions of people, armed in the holy cause of liberty".
1770s, "Give me liberty, or give me death!" (1775)
Context: They tell us, sir, that we are weak; unable to cope with so formidable an adversary. But when shall we be stronger? Will it be the next week, or the next year? Will it be when we are totally disarmed, and when a British guard shall be stationed in every house? Shall we gather strength by irresolution and inaction? Shall we acquire the means of effectual resistance by lying supinely on our backs and hugging the delusive phantom of hope, until our enemies shall have bound us hand and foot?
Sir, we are not weak if we make a proper use of those means which the God of nature hath placed in our power. Three millions of people, armed in the holy cause of Liberty, and in such a country as that which we possess, are invincible by any force which our enemy can send against us. Besides, sir, we shall not fight our battles alone. There is a just God who presides over the destinies of nations, and who will raise up friends to fight our battles for us. The battle, sir, is not to the strong alone; it is to the vigilant, the active, the brave.

People's War, People's Army (1964)

Source: The Future As History (1960), Chapter III, Part 12, The Deepening Confusion, p. 170

Prayer to Saint Michael (1888)
Context: O Glorious Archangel St. Michael, Prince of the heavenly host, be our defense in the terrible warfare which we carry on against principalities and Powers, against the rulers of this world of darkness, spirits of evil. Come to the aid of man, whom God created immortal, made in His own image and likeness, and redeemed at a great price from the tyranny of the devil.
Fight this day the battle of the Lord, together with the holy angels, as already thou hast fought the leader of the proud angels, Lucifer, and his apostate host, who were powerless to resist thee, nor was there place for them any longer in Heaven.

Federalist No. 10
1780s, Federalist Papers (1787–1788)

Context: The tank, the B-52, the fighter-bomber, the state-controlled police and military are the weapons of dictatorship. The rifle is the weapon of democracy. Not for nothing was the revolver called an "equalizer." Egalite implies liberte. And always will. Let us hope our weapons are never needed — but do not forget what the common people of this nation knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny.

Abbey's Road (1979)

Book I, line 128 (tr. J. D. Duff).
Tho. Hobbes's translation:
: The side that won the Gods approved most,
But Cato better lik'd the side that lost.
Jane Wilson Joyce's translation:
: The conquering cause pleased the gods, but the conquered pleased Cato.
Pharsalia