The reaction of one Jewish merchant in Paducah, Cesar Kaskel, touched off a firestorm. He took off on what Mr. Sarna calls a “Paul Revere-like ride to Washington.” He alerted and roused the press. And he managed, through a congressman, to gain access to Lincoln, who “turned out to have no knowledge whatsoever of the order, for it had not reached Washington.” Here is an excerpt from the overblown conversation Kaskel claimed to have had with Lincoln:

Lincoln: “And so the children of Israel were driven from the happy land of Canaan?”

Kaskel: “Yes, and that is why we have come unto Father Abraham’s bosom, asking protection.”

Lincoln: “And this protection they shall have at once.”

The real effects of Grant’s action took the form of similarly extreme, sometimes hyperbolic responses from American Jews. Suddenly everything about them, including the question of exactly what “American Jews” means in terms of allegiance, was part of the debate. Mr. Sarna delivers a careful, warts-and-all accounting of the ugliness surrounding all sides of this incident, right down to quoting the fearful, competitive, even hostile attitude some Jews held toward newly freed slaves. Lincoln’s Emancipation Proclamation had arrived on Jan. 1, 1863, right between the enforcement and revocation of Grant’s order.

“Historians, understandably, have played down this fear, not wishing to besmirch the reputations of some of American Jewry’s most illustrious leaders whose words, in retrospect, are painful to read,” Mr. Sarna writes.

“Painful” is an understatement.

One of the most egregious came from Isaac Leeser, editor of The Occident, a Jewish publication: “Why are tears shed for the sufferings of the African in his bondage, by which his moral condition has been immensely improved, in spite of all that may be alleged to the contrary, whereas for the Hebrews every one has words of contempt or acts of violence?”