A low-key but informative memoir of WW II service with the OSS from the late director of the CIA. Much of the episodic narrative is based on Casey's personal experiences and observations as a London-based staff officer to Maj. Gen. William J. Donovan. Toward year-end 1944, the author (then 31) was named chief of secret intelligence for the whole of the European theater. In this position, which required him to resign his naval commission, he headed the first fully independent effort by US forces to put agents behind enemy lines. Earlier on, the British had controlled virtually all clandestine missions, keeping their American and other allies on comparatively short leashes. Casey makes a fine job of sorting out the various French resistance groups--FFI, Maquis, et al.--which seemingly spent as much time fighting among themselves as battling German or Vichy foes. He also offers instructive briefings on the Belgian and Dutch undergrounds, whose potential went largely unrealized. Covered as well on the basis of firsthand knowledge are the deceptions that helped divert 22 Nazi divisions from the D-day front, acrimonious debates on the relative merits of sabotage (which brought reprisals) and air strikes (which caused civilian casualties), and the problems caused by FDR's insistence on unconditional surrender. The latter difficulties were compounded by the widespread credence given a Bavarian redoubt--a nonexistent bastion that Casey believes the OSS could and should have debunked. The text includes evenhanded tributes to such contemporaries as Donovan, Col. David Bruce, Richard Helms, and Allen Dulles, plus occasionally acerbic judgments on military commanders (e.g., ""His [Field Marshal Montgomery's] Rhine journey would equal Siegfried's. . .""). In a preface, Casey asserts he wrote the book to show how covert operations in which local dissidents played leading roles ""saved blood and treasure in defeating Hitler."" Such capabilities, he argues, may prove ""more important than missiles, nuclear bombs and satellites in meeting crises yet to come""--in particular, threats mounted by a totalitarian power. All in all, a welcome addition to the cloak-and-dagger genre.