Stirling Silliphant Screenplay

Wasn't sure where to put this query, so forgive me if this is the wrong place.

Some time ago I read online where Silliphant began working on a screenplay based on the conflict in Vietnam (set, I believe, during the early days of American Involvement) but stopped before completion. I tried to locate the article again but cannot find it (or any other mention of it) - does this sound familiar to anyone?