The label said "General Stilwell's talk to Commonwealth Club of San Francisco, Feb. 13 1946," but could it be trusted? I've written about the problems with labels before. This one was attached to a compact sound cassette, which is at least one generation removed from the laquer disc on which a speech given in 1946 would have been recorded. So the person who originally recorded the speech--the most reliable source of information--probably did not write this label.
Any speech given at the Commonwealth Club would be documented in the club's records, which are at the Hoover Archives. (Even Herbert Hoover's nine off-the-record talks at the club show up in various ways in the club's publications and internal files, though the cursory information available lives up to their billing.) Searching this collection for a Stilwell speech yielded only one, by Joe Stilwell Jr. in 1966.
Thinking the speech itself might have clues, I cued a digital copy of the recording on my computer. It begins with applause, and then a man addresses the mayor and friends of San Francisco. He mentions that the war with Japan ended seven months ago, and in closing he refers to the Sixth Army at the Presidio, all of which places the talk in San Francisco in March 1946. This meshes with Stilwell's assignment as commander of the Sixth Army, which was reactivated effective March 1, 1946, at the Presidio of San Francisco (he died there that October). But we still didn’t have a venue.
A speech by a big war hero like Stilwell was sure to get press attention, especially given Stilwell's frank and colorful style. A search for Stilwell in newspaper indexes for 1946 yielded a likely hit, on March 29, 1946. The San Francisco Chronicle's front page barked, "Gen. Stilwell Talks Back: 'Army Caste System Sounds Nasty, but Discipline Is Vital.'" The article reports that Stilwell "covered the caste system, Army brass hats, the atomic bomb, and charges of undemocratic procedures in the Army," which closely parallels the arc of the recorded speech. Stilwell's quotes in the newspaper synched with the phrases I heard, which is about as definitive an identification as we're ever likely to have for this sound recording. And the venue? San Francisco's Chamber of Commerce luncheon on March 28, 1946. So much for labels.