THE SECRET WAR AGAINST HITLER; By William Casey; Regnery Gateway; 304 pages; $19.95.

Here is a voice from the grave, telling history - his way. A year after his death, we find William Casey still at it, still making a case for the cause of his final years: a powerful Central Intelligence Agency, secure in public standing, unhampered, uninhibited, and unapologetic in its actions, including the combat intelligence and guerrilla operations on which the book centers.Casey somehow managed to write this book during 1985 and '86, despite his intense CIA work and declining health. Clearly, it meant a lot to him. But why?

Casey was upholding, not only the CIA's legitimacy in American life, but also his own in the pantheon of American intelligence heroes, as against the Ivy Leaguers who had joined the CIA early in the cold war, while he was making a fortune as a tax lawyer. This book reminds everyone that he, a man of modest background, had achieved much in the Office of Strategic Services - the CIA's predecessor - and stood as close to William J. Donovan, the charismatic godfather of American intelligence, as the Ivy Leaguers did.

Casey is at one with most CIA people in harking back to the glory days of World War II, when the OSS recruited the best and the brightest to fight the good fight. That times have changed, that confronting Gorbachev or Qaddafi is hardly analogous to fighting Hitler, and that policy by nostalgia signifies intellectual bankruptcy, is not for him to grasp.

Instead, he recalls a Washington brimming with energy and purpose in 1943; a London revving up excitedly in early 1944 for the longest day in Normandy; and a Paris liberated by the Allies - and the OSS - in that glorious August. Casey was there, a small but hardworking cog, rubbing elbows with the great and near-great - though he is modest, no name-dropper - and finding in Donovan a mentor and father figure.

Donovan would use anyone, left, right, or center; so did Casey. Donovan identified with American big business; so did Casey. Donovan crammed his spare minutes with reading; so did Casey. But this reading was essentially functional, operational, utilitarian. Judging by this book, it neither broadened Casey's outlook nor taught him to respect the truth.

For this book is highly tendentious, its data shaped and manipulated to bolster his case for strong intelligence systems, and not to investigate what the OSS actually accomplished while supporting French guerrillas in the summer of 1944.

The thrust is that powerful outside - that is, American - support will rouse indigenous peoples against their oppressors. Witness the growing French resistance movement from May to September of 1944: The OSS and the British Special Operations Executive parachuted in weapons and personnel, thus helping the French contribute enormously to German defeat; Casey even titles one chapter "France Liberates Itself." The analogies to the Contra war are obvious.

So are the flaws in the argument. By their very nature as light forces, with little firepower, cohesion, or logistical support, the French could only snipe, skirmish, and sabotage. The heavy lifting fell to the Anglo-American armies, attacks on German road convoys to Allied tactical air power. Casey's anecdotes about brave French fighters are long on drama, short on assessment.

Nowhere does this lawyer making a politically tinged case strike a balance. His argument, ironically enough, parallels that of radical historians, whose myth is that of 1792, of a mass uprising, passionate and brave, against the hated invaders. Anyone who has seen "The Sorrow and the Pity" (969), a film about the Nazi occupation of France, knows this is sheer blarney.

Writing history requires refined skepticism, the readiness to question all received truths. So thoroughly politicized a personage as William Casey (onsider his gibes against Franklin Roosevelt and the unconditional surrender doctrine, whose subtle historiography Casey overlooks) might have written an intriguing memoir, but a history? Never!