In the last half-century of philo-Semitism — which has produced fewer oha-vay yisrael (literally, lovers of Israel) than one might have hoped for, but more than one might have feared — Winston Churchill stands out as a sophisticated advocate of this “scattered and unattractive tribe,” as the Jews were once described by H.H. Asquith, Churchill’s mentor, who preceded him by several decades as Prime Minister of England. Without Churchill’s refusal to countenance and appease Hitler’s growing war machine, the world would look like a different place today — and there would have been undoubtedly fewer Jews left standing when Hitler was finally defeated. Without Churchill’s impassioned (if also politically expedient) support for a nascent Zionism, Jews might have had no country to call their own. In 1908 Churchill sent a message to the annual conference of the English Zionist Federation, in which he stated that he was “in full sympathy with the historical traditional aspiration of the Jews. The restoration to them of a centre of true racial and political integrity would be,” he wrote, “a tremendous event in the history of the world.”

Indeed, as Martin Gilbert suggests in his consistently absorbing “Churchill and the Jews: A Lifelong Friendship” (Henry Holt, 384 pages, $30), there have been few figures in high office in any country who not only admired the Jews for their unique qualities — “the spirit of their faith and race” as well as their “peculiar genius” — but who also were able to accept them as a people apart, deserving not only tolerance but genuine respect for their differences. Already as a young boy, Churchill was inclined toward the Jewish cause, though he was raised in a culture marked by an entrenched and adamant anti-Semitism that was all the more difficult to combat because of its thin patina of civility. Churchill’s own cousin, the 9th Duke of Marlborough, referred to the editor of the Daily Telegraph as “that dirty little Hebrew” and insisted in a letter he wrote to Churchill early in his political career that “Jews cannot be dealt with with the same good feeling that prompts the intercourse between Christians.”

Churchill came by his bias honestly: His father, Lord Randolph Churchill, was known for his friendship with a select group of distinguished Jews, including Nathan “Natty” Rothschild, the head of the British branch of the Rothschild banking family and the first Jew to serve in the House of Lords, and the banker Sir Ernest Cassel. After nursing initial qualms about the marriage of his 22-year-old daughter Sarah to the twice-divorced Austrian-born Jew Victor Oliver von Samek (on grounds of his suspiciously busy marital life rather than on grounds of race), he came to like and respect his son-in-law.

Churchill’s sympathy was not merely a private matter, however. In 1914, right after Britain declared war on Germany, Churchill, then the 37-year-old Home Secretary, intervened to have Theodor Herzl’s son, Hans — who otherwise would have acquired immediately the status of enemy alien — made a naturalized citizen. The previous year, Churchill had resigned from a social club that had blackballed a friend of his, a liberal MP, who also happened to be Jewish; he eventually founded a club named The Other Club, where Jews (at least auspicious Jews, such as James de Rothschild) were welcome.

Throughout his long and phoenix-like political career, Churchill remained remarkably attuned to the undercurrent of implacable animus toward the Jews — “the hereditary antipathy which exists all over the world to the Jewish race,” as one member of Parliament reminded Churchill, in an effort to get him to abandon his support of the Zionist cause. He was especially sensitive to the hostility of the British administrators in Palestine during the period of the Mandate. “Of every fifty officers who came back from the Middle East,” he told his Chiefs of Staff Committee in 1944, “only one spoke favorably of the Jews.” Anthony Eden, who served as Foreign Secretary during the crucial World War II period, was not atypical in his views; according to his own Private Secretary, Eden was “immovable on the subject of Palestine. He loves Arabs and hates the Jews.”

Churchill was too canny a political creature to offer wholesale endorsement of Jews and Jewish causes within his own country, forced as he was to navigate within the culture of anti-Semitism, often ingeniously articulated, which existed at the highest levels of British government; he had always recognized the need for stealth and cunning when pushing the Jewish cause. When Lloyd George was forming his Cabinet in the immediate wake of World War I, Churchill sent him a handwritten letter advising caution when it came to choosing members of the coalition: “There is a point about Jews – you must not have too many of them,” he wrote, going on to add “Three Jews among only seven Liberal Cabinet Ministers might I fear give rise to comment.” (In the event, only one Jew was appointed.)

Churchill’s immediate predecessor, Neville Chamberlain, perhaps most exemplified this disdainful and subfusc attitude. In a letter to his sister, written right after his notorious White Paper was voted in by a large parliamentary majorityin1939, Chamberlain commented with chilling casualness on the Nazi persecution of the Jews: “No doubt Jews aren’t a lovable people; I don’t care about them myself; but that is not sufficient to explain the Pogrom.” The White Paper, of course, put a quota on Jewish immigration to Palestine (75,000 during the coming five years) just as the need for such a haven became ever more dire, the better to protect the Arab majority in Palestine and thereby keep the Muslim world happy. “If we must offend one side,” Chamberlain stated, “let us offend the Jews rather than the Arabs.” (An irrational fear of Arab “street” reaction, fueled by British administrators and Arab leaders — who already then spoke of the “paradise” that awaited Arab martyrs to the anti-Jewish cause — in the Middle East guided the geopolitics of the region then as it continues to do now.) Churchill first visited Palestine in 1921 and returned enthused about the Jewish presence, a response which led to his consistent thwarting of the White Paper. His own prejudices, it should be noted, ran in the other direction, toward intransigent anti-Islamic attitudes: “It is a lower manifestation,” he remarked, “the Arab.”

After the emergence of Hitler and the rise of Nazism, Churchill became more outspoken in his concern for the fate of not just British Jews but for the Jewish situation in its entirety. With one exception, Churchill made the matter of Nazi tyranny very much his business. In September of 1937, in an effort to persuade Hitler to become a “Hitler of peace,” Churchill stated that although “We cannot say we admire your treatment of the Jews … of Germany, these matters, so long as they are confined inside Germany, are not our business.” But only three months after making this abortive appeal, he directly addressed the issue of the “abominable persecution” of the Jews in the House of Commons: “It is a horrible thing that a race of people should be attempted to be blotted out of the society in which they have been born.”

In 1939, Churchill met with an Albanian diplomat in an effort to help secure a sanctuary for German and Austrian Jews; although the diplomat, a member of one of Albania’s leading families, came back with authorization to negotiate, Mussolini put an end to Albania’s independence within the month. That Hitler had a darker and more global vision of annihilation in mind than simply making Germany Judenrein was not yet apparent to even those who were keeping a leery watch on him, but Churchill would rise to the occasion with due alacrity and forcefulness. Not surprisingly, his longstanding protective attitude toward the Jews inevitably led to charges, from the very beginning of his career, that he was in cahoots with them; the ever-litigious Lord Alfred Douglas brought court papers against Churchill for being in the employ of the Jews during and after World War I, and Goebbels described him as an “instigator-international.”

Despite his generally impassioned support of Jews and their collective fate, Mr. Gilbert’s account makes clear that it was, as Chaim Weizmann put it , Churchill’s “unceasing interest in Zionist affairs” that was most striking. Although his original stance on the Zionist cause was fueled by his fear that British Jews would succumb to Bolshevism, Churchill’s commitment to the Jewish right to a national homeland developed over time and became infused by a keen understanding of the historical powerlessness that the establishment of a Jewish state was designed to redress. During his tenure as Secretary of State under Lloyd George, he refused to repudiate the Balfour Declaration under persistent Arab pressure. Contemplating the Partition Question in 1937, Churchill described, in an article for the Evening Telegraph, “the plan of cutting Palestine into three parts” as “a counsel of despair.” And in his speech against the proposed Arab veto on all Jewish immigration after 1944, he burst forth in all the oratorical splendor that was at his command: “Now, there is the breach, there is the violation of the pledge; there is the abandonment of the Balfour Declaration; there is the end of the vision, of the hope, of the dream…”

“Churchill and the Jews” brings together two of Martin Gilbert’s persistent passions: Among his vast output, he has written an eight-volume biography of Churchill and at least as many books on various aspects of Judaism, ranging from histories of Israel to histories of the Holocaust. This book reflects his gifts — he is a demon researcher, drawing on a trove of private correspondence, archival material, and previously unpublished government documents, and a fleet-footed writer — as well as his ideological agenda, which is to link intextricably the ideas and affections of one of the greatest statesmen of modern times with an ancient people and their road to statehood. In order to achieve this end, Gilbert has had to pass lightly over some of Churchill’s less attractive attitudes and positions, including his occasional sacrificing of Jewish interests to British ones. (After having promised Weizmann immediate action following the end of World War II, Churchill put off the question of Jewish statehood “until the victorious allies are definitely seated at the Peace table.”) Still, by and large, his assessment is an accurate one, and goes some way toward restoring the luster of Churchill’s reputation, which, in one of those posthumous reversals that seem to always follow the initial mythologizing of iconic figures, has suffered a downgrading in recent years. Churchill was undoubtedly a man of complex and large appetites, with a hefty yet frail ego that required ongoing boosting from his associates and his wife. And yet, whatever his genuine flaws, he was, redeemingly, “too fond of the Jews” — an ostensible weakness that Mr. Gilbert was warned of by a fellow parliamentarian of Churchill’s before he embarked on his biography. In return, he is owed a permanent debt by Jews everywhere, if not of gratitude then in recognition of an abiding and empowering friendship.

Ms. Merkin is the author of a novel, “Enchantment,” and a collection of essays, “Dreaming of Hitler.” She is a contributing writer to the New York Times Magazine and writes the Provocateur column in Elle.