It occurred to me that I know of more set designers (Joel Schumacher, WC Menzies, Lourie, Daniel Haller...) who became directors than assistant directors who did. Is it strange that so few artists with "director" already in their name have gone on to distinguish themselves in this capacity, or am I simply missing something?

It's far more common (and appropriate) for second unit directors to move up, as they're actually doing the job, and with a certain autonomy. The key word in 'assistant director' is 'assistant'. As in, 'assistant *to* the director'.

Assistant Directors tend to do crowd control on sets, usually managing the extras. There really isn't much in the way of creativity to it. One A.D. who famously went on to direct was Robert Aldrich, a college football player who'd walked out on his family's money (his first cousin was Nelson Rockefeller!) to start at the bottom at RKO as an assistant prop man or something. As Assistant Director, look who he worked with: Jean Renoir, Charlie Chaplin, William Wellman, Lewis Milestone, Robert Rossen, Joseph Losey. Not a bad bunch to learn from, huh?

Of note is the late David Tomblin - he didn't direct a feature, but directed episodes of UFO, SPACE:1999 and THE PRISONER (which he also produced)...

David Tomblin

In the early 1980's I met Joe Ray, who was an AD on most New York based film in the 80's & 90's... he encouraged me to take the Director's Guild trainee test (which I failed, possibly because of the notoriously bizarre "psychological" part of the exam, which asked weird questions like "Do you hear voices?", "Do you like manly women?" and "Do you like to play 'Drop the handkerchief?'")... Anyway, from the 90's on he worked mostly on Black films directed by some of the many Black filmmakers he mentored. But he hasn't to date directed one himself (to my knowledge).

Since doing the post on Aldrich above I pulled out a book of Aldrich interviews and read it. To correct one thing in my post: he started out as a production clerk, which he describes as “the lowest form of human life here, the guy below the book-keeper and below the tea boy.”

Here’s a good section, taken from his remarks before an AFI Seminar, on why Aldrich thinks starting out as an assistant director is a great way to learn on the job:

“I’ve always thought that working your way up from third or fourth or fifth assistant is like getting paid to go to college. Working with great directors—and terrible directors—is the greatest education possible. But that is not a popular belief any more. For a while in the forties, the concept was to bring stage directors to California. They became directors, some pretty good, some not so good. Then, with the success of Bobby Wise and Mark Robson and John Sturges, there was the idea of making cutters directors. It became an instant trend. But if someone asks me, I always say, ‘I truly believe that being an assistant is the best way.’

“When I was an assistant, in the forties, you really were the director’s assistant. You worked for him and because of him. Quite often, he took you from job to job. You weren’t an extension of the production office. But today, with the economics of film and particularly of television, that is not necessarily true. In television the directors rotate, but the assistants stay on the show. The assistants’ loyalty, for their own survival, happens to be more to the production office than to the director. Consequently, the director is not as friendly and not as willing to share his time and ideas as he was previously.”

In another interview he describes how they had to reshoot an intricate patrol sequence that took all day to film for William Wellman's THE STORY OF G.I. JOE (1945) because Aldrich, as A.D., realized afterwards that one of the actors featured in it had already been killed in a previously shot scene that took place before this one. Aldrich says it was his responsibility to keep that straight and he took the blame for it. (I thought that was the Script Supervisor's job.) Aldrich also claims to be the one to recommend to Wellman that Robert Mitchum, who was doing B-westerns at RKO at the time, be cast in this. It was Mitchum's breakout role and it got him his only Oscar nomination. Mitchum later turned down Aldrich as director for THE YAKUZA.

Another one: Michael Powell, who started out as AD to Rex Ingram. Of course, the industry was still a-bornin' back then.

Another early one was Clarence Brown, who started out as an AD to Maurice Tourneur. Fascinating, if rambling, story about him here.

The guy who taught me most of what I know about assistant directing was John Board, who was David Cronenberg's AD during the 1980s. John had already been a director and liked to joke that his only feature, THE MERRY WIVES OF TOBIAS ROURKE, now lived contentedly in a can under his bed. But John had tremendous personal charm and authority, so he had a gift for keeping Cronenberg's sets relaxed and pleasant yet always alert and professional.

Another example of a director who moved up from second unit direction is John Glen, who directed action shots for several Bond films before ascending to full control of one. (Well, as close to full control as any director enjoys on a Bond film.)

In the Yule LOSING THE LIGHT hardcover, Terry Gilliam notes that David Tomblin rescued BARON MUNCHAUSEN from its near-fatal chaotic slide off a high cliff by sorting the production out, steering things in the right direction and getting the Italian crew and general shoot moving efficiently at a crucial, last-minute point when almost no-one was able to. Tomblin is granted a highlighted 'Man of the Match' credit at the end of the film. Maybe we'll hear more about Tomblin on the upcoming DVD.

Of a more current lot Peter Medak, Michele Soavi and Daniel Attias were all Assistant Directors, and I think Steve Miner was too. Didn't a number of the people that passed through the A.I.P. and New World stables - Peter Bogdanovich, Jack Hill, Monte Hellman, Jonathan Demme, etc - work in this capacity at some point or another?

Hammer veteran Jimmy Sangster acted as an AD among the many hats he wore during his time with the studio. For that matter Roy Ward Baker, John Gilling, and Don Sharp were also ADs at one point or another.

Directors like Guy Hamilton, Andrew McLaglen, George Cosmatos, and James Fargo all worked as assistants early in their careers.

Going back much farther didn't film makers such as David Lean, Carol Reed, Howard Hawks, John Ford, W.S. Van Dyke, Victor Fleming, Michael Curtiz, Henry Hathaway, and Raoul Walsh all work as Assistant Directors?