“Gentlemen, you have fought like lions and been led by donkeys.”

Attributed to Napoleon in Napoleon (1941) by Yevgeny Tarle, this is a variant of an ancient proverb often attributed to many military and political figures, including Alexander the Great, and the even earlier figure Chabrias (Χαβρίας).
Misattributed

Attributed to Alexander, as quoted in The British Battle Fleet: Its Inception and Growth Throughout the Centuries to the Present Day (1915) by Frederick Thomas Jane, but many variants of similar statements exist which have been attributed to others, though in research done for Wikiquote definite citations of original documents have not yet been found for any of them:
I should prefer an army of stags led by a lion, to an army of lions led by a stag.
Attributed to Chabrias, who died around the time Alexander was born, thus his is the earliest life to whom such assertions have been attributed; as quoted in A Treatise on the Defence of Fortified Places (1814) by Lazare Carnot, p. 50
An army of stags led by a lion would be better than an army of lions led by a stag.
Attributed to Chabrias, A History of Ireland (1857) by Thomas Mooney, p. 760
An army of stags led by a lion is superior to an army of lions led by a stag.
Attributed to Chabrias, The New American Cyclopaedia : A Popular Dictionary of General Knowledge (1863), Vol. 4, p. 670
An army of sheep led by a lion are more to be feared than an army of lions led by a sheep.
Attributed to Chabrias, The Older We Get, The Better We Were, Marine Corps Sea Stories (2004) by Vince Crawley, p. 67
It is better to have sheep led by a lion than lions led by a sheep.
Attributed to Polybius in Between Spenser and Swift: English Writing in Seventeenth Century Ireland (2005) by Deana Rankin, p. 124, citing A Contemporary History of Affairs in Ireland, from 1641 to 1652 (1880) by John Thomas Gilbert Vol. I, i, p. 153 - 157; but conceivably this might be reference to Polybius the historian quoting either Alexander or Chabrias.
An army composed of sheep but led by a lion is more powerful than an army of lions led by a sheep.
"Proverb" quoted by Agostino Nifo in De Regnandi Peritia (1523) as cited in Machiavelli - The First Century: Studies in Enthusiasm, Hostility, and Irrelevance (2005) by Mathew Thomson, p. 55
Greater is an army of sheep led by a lion, than an army of lions led by a sheep.
Attributed to Daniel Defoe (c. 1659 - 1731)
I am more afraid of one hundred sheep led by a lion than one hundred lions led by a sheep.
Attributed to Charles Maurice de Talleyrand-Périgord (1754 – 1838) Variants: I am more afraid of an army of 100 sheep led by a lion than an army of 100 lions led by a sheep.
I am not afraid of an army of one hundred lions led by a sheep. I am afraid of army of 100 sheeps led by a lion.
Variants quoted as an anonymous proverb:
Better a herd of sheep led by a lion than a herd of lions led by a sheep.
A flock of sheep led by a lion was more powerful than a flock of lions led by a sheep.
An army of sheep led by a lion would defeat an army of lions led by a sheep.
It were better to have an army of sheep led by a lion than an army of lions led by a sheep.
An army of sheep led by a lion, will defeat an army of lions led by a sheep.
An army of sheep led by a lion would be superior to an army of lions led by a sheep.
Unsourced attribution to Alexander: I would not fear a pack of lions led by a sheep, but I would always fear a flock of sheep led by a lion.
As one lion overcomes many people and as one wolf scatters many sheep, so likewise will I, with one word, destroy the peoples who have come against me.
This slightly similar statement is the only quote relating to lions in The History of Alexander the Great, Being the Syriac Version of the Pseudo-Callisthenes (1889) as translated by E. A. Wallis Budge, but it is attributed to Nectanebus (Nectanebo II).
Disputed

Taking Chances (1944)

Not found in Augustine's works, it is stated in Fauxtations: Because sometimes the Internet is wrong : St. Augustine: The Truth is Like a Lion (18 October 2015) https://fauxtations.wordpress.com/2015/10/18/st-augustine-the-truth-is-like-a-lion/, that this is very likely a summary derived from statements of Charles Haddon Spurgeon about the "Word of God" or "the pure gospel", and the Bible:
:: The Word of God can take care of itself, and will do so if we preach it, and cease defending it. See you that lion. They have caged him for his preservation; shut him up behind iron bars to secure him from his foes! See how a band of armed men have gathered together to protect the lion. What a clatter they make with their swords and spears! These mighty men are intent upon defending a lion. O fools, and slow of heart! Open that door! Let the lord of the forest come forth free. Who will dare to encounter him? What does he want with your guardian care? Let the pure gospel go forth in all its lion-like majesty, and it will soon clear its own way and ease itself of its adversaries.
::* The Lover of God’s Law Filled with Peace (January 1888)
: and the earlier:
:: There seems to me to have been twice as much done in some ages in defending the Bible as in expounding it, but if the whole of our strength shall henceforth go to the exposition and spreading of it, we may leave it pretty much to defend itself. I do not know whether you see that lion — it is very distinctly before my eyes; a number of persons advance to attack him, while a host of us would defend the grand old monarch, the British Lion, with all our strength. Many suggestions are made and much advice is offered. This weapon is recommended, and the other. Pardon me if I offer a quiet suggestion. Open the door and let the lion out; he will take care of himself. Why, they are gone! He no sooner goes forth in his strength than his assailants flee. The way to meet infidelity is to spread the Bible. The answer to every objection against the Bible is the Bible.
::* Speech at the Annual Meeting of the British and Foreign Bible Society "The Bible" (5 May 1875), in Speeches by C. H. Spurgeon at Home and Abroad (1878) edited by G.H. Pike https://books.google.com/books?id=j_0CAAAAQAAJ&pg=PA17&lpg=PA17#v=onepage&q&f=false
Misattributed

Paul Blenkiron, Stories and Analogies in Cognitive Behaviour Therapy (2010), , p. 43

"Thank goodness I was not on the donkey at the time, or I would be lost too."
Paul Blenkiron, Stories and Analogies in Cognitive Behaviour Therapy (2010), ISBN 047005896X, p. 43

Source: Lover Awakened