This installment of my "Quick Bits" series takes a quick look at the stars found on the 1937 Antietam half dollar - there are a total of five, all on the coin's obverse. Do you know why there are only five?
Two stars are seen near the left rim below the coin's vertical center, flanking "IN GOD WE TRUST." These stars are meant to symbolize the rank of William McClellan, he was a Major General in the Union Army which accorded him two stars on his collar. (McClellan's portrait is depicted on the coin to the left, behind Lee's.)
Union General George B. McClellan (with two stars on shoulder vs. collar)
In the same vertical position near the right rim are seen three stars, these represent Robert E. Lee's rank of General in the Confederate Army. Some descriptions of the coin indicate that the three stars represent Lee's last rank (Colonel) while within the Union Army, others have stated that the three stars recognized Lee's preference to wear the three stars of a Confederate Colonel. The latter is close to correct, the former not so much.
In actual fact, the official insignia for a Confederate General and a Confederate Colonel each featured three stars. The difference was that for a General, the three stars were encircled by a wreath whereas a Confederate Colonel wore three stars w/o a wreath. Lee did, however, demonstrate a preference for the unadorned three stars of a Colonel, almost always wearing just three stars on his collar (sans wreath); the wreath insignia can be seen in photographs of other Confederate Generals.
Confederate General Robert E. Lee (with three stars on collar, no wreath)
Confederate General Benjamin Huger (with three stars within wreath on collar)
So, the three stars used by William Marks Simpson for his Antietam half dollar design were accurate in number for a Confederate General if not in actual arrangement (which was likely his intention so that the stars fit unobtrusively with his design's overall aesthetic).

You can read more about the coin here:
1937 Battle of Antietam Half Dollar and here:
1937 Battle of Antietam Half Dollar - Revisited.
Also.
Read More: Commems Collection