Why did Napolean tuck his hand under his jacket in portraits? Was he hiding something? Did he not know what to do with his hands? Is this how people posed for paintings in his era? Straight dope, please.
The answer is, of course, that he was holding up his pants. 
http://www.regiments.org/wombats/classics/boney.txt
has an interesting thread about the various theories as to why Boney did that
Cecil’s theory
Oddly enough, just yesterday I was reading the book Do Fish Drink Water? by an author that I can’t recall right now (and am too lazy to look up at the moment!), and this issue was addressed there.
The author of that book says that the hand in the coat pose was simply a common pose at the time for portraits… especially portraits of famous or important men…
I’d tend to second Astroboy’s comment. When sitting for a portrait, you need to do something with your hands. Putting it into your shirt was probably one option.
I’ve heard theories that it had to do with Napoleon’s stomach problems, but I tend to think the simpler explanation is more likely.
There was already a thread on this:
http://boards.straightdope.com/sdmb/showthread.php?threadid=41323
Good idea to search first before starting a thread. But note the spelling: Napoleon. With the wrong spelling a search won’t work.
The “I Dream of Jeannie” theory: those uniforms were darn itchy. 
It can’t be specific to Napoleon, since there exists a portrait of General Washington, around the time of the American Revolution, posing with his hand in his vest, and this was quite a few years before Napoleon made the scene.
His hand was amde of gold, of course, and too heavy to support otherwise.
Haven’t you seen Time Bandits?
I thought I’d look up the actual picture we were talking about:
- The Emperor Napoleon in His Study at the Tuileries Somehow this doesn’t look like the one I was remembering, but I couldn’t find one closer.
- Here’s another one. Note the position of the sword in relation to the hand in question. Bonaparte at First Consul
- And one that shows both hands: Napoleon as Master of Europe
I’ve read all of the previous links, and I’m not satisfied with any of the theories posted so far.
**There was something wrong with him – ulcer, itching, disfigured hand: ** Portraiture is not photography. There is no need for the artist to portray flaws or non-flattering behaviors. Portraits in the heroic mode especially are going to be designed and executed to portray the subject in the best possible light. In addition, at least two different web pages mentioned that the first portrait above was painted without Napoleon sitting for it.
The hands need to be doing something and/or it was a popular way to portray men How to position the hand is part of the portrait composition; however, there are many options available that are more flattering than this one. Among other things, this distorts the subjects clothing, and make him look like he’s itching himself. In contrast, note in the third portrait how one of the hands is holding the cloak, which allows the painter to show off the richness of the cloak, not to mention his skill in painting drapery. In addition, one of the web pages mentioned earlier in the thread that only 11 of a 119 portraits have this hand position used, which doesn’t sound like a great deal of popularity. Finally, one of the web pages I ran into made a point of how the first portrait above was specifically composed to highlight Napoleons generalship, emperorship, and civic accomplishments (http://www.nga.gov/collection/gallery/gg56/gg56-45831.0.html )
Keeping the hand warm in preparation for sword use I think portrait two above argues against that fairly well. Besides, why would Napoleon be warming his hand when he was in his study, and why would Handel or Gainsborough be doing this? Also, it seems to me that putting your hand here would interfere with your ability to draw your sword easily – maybe someone with actual experience could comment on that.
IMO, there is some meaning to the hand position, that we just don’t know about anymore, Napoleon’s portrait having overwhelmed any previous significance. It may have indicated some sort of status that everyone was well enough aware of that no one thought to note why they were doing that. One theory that I heard a long time ago was that this was done by members of a fraternity of horsemen based in Spain; unfortunately this was in a particularly schmaltzy historical fiction book, so the source is highly suspect. But that general explanation feels right to me, it is consistent with the message of the first portrait, and with other portraits – for instance, George Washington was painted in this fashion (and it was prior to the first painting referenced above).
Oh, fuss
Sorry, Jomo, I knew I had read that last tidbit somewhere, but after Cecil, three web discussions and a bunch of web pages, I was confused.
Surely, I’m not the only one who remembers that it’s because he kept a Drake’s coffee cake in there!
I read in an art journal once upon a time that many painters did this because hands are the most difficult and time consuming thing to paint, and in that period and before, not many pants had pockets, so it was easier to tuck a hand inside a coat, lay one over the other,or place it behind the back. It also allowed the arm to bend somewhat, giving the portrait a little more body and sense of “action”. After hundreds of years of that being the “style for men of high regard”, it seems that it ended with the advent of the camera. I don’t recall ever seeing any early photograph portraits done that way, so the explanation, whether true or not, makes more sense to me than anything else.
Here’s a portrait of George Washington by Peale in 1772. I am of the opinion that Napoleonic portraits in which he has his hand in his tunic date from about 30 years later.
So, unless Washington had a terrible itch, or was making ready to draw his sabre, one might conclude that the persons who champion stylistic reasons have a leg up.
I go with the “hands need to be doing something”. A portrait would look damned un-dynamic if the guy was standing there with both hands hanging at his side. Some fashion expert on this board can tell me for sure if in any of the portatits shown there are pockets on Bonaparte’s trousers. I don’t think so. But in any case, if there were and he was standing with his hands in “Air Force Gloves”, he’d look like was waiting for a bus or something.
If it was up to you, what would you have him do with his hands?
I subscribe to both the “do something with the hands” and a modified “hands are hard to paint” theories.
Aside from grasping the lapels (which in Nappy’s case, were much different than suit coats of today), what else is the subject to do? Keep in mind that the notion of “posing” may have been very different 200 years ago than it is today. Rather than straining to keep from looking contrived, they may have wanted to look “posed” for a formal portrait.
As for hands being hard to paint, well, yeah, they are, but we’re talking about a professional portrait artist, not someone who likes to doodle. They knew how to paint hands. Problem is, in something as static as a painting or a sculpture, hands tend to look oversized. Hands are bigger than people think. They completely cover the face, but because they are not usually still, it’s hard to notice their size relative to the rest of the body. As a friend of mine said about the statue of David, “I don’t like it, his hands are too big and his penis is too small.”
A portrait artist may have had his subject hide one hand behind his back (natural, if you’re not facing head-on) and put the other where it’s full size doesn’t show as much. In the case of a man wearing an 18th Century French dress uniform, it would be in the vest.
Composition and line considerations would also come into play.
But there are so many things that you can do with hands, that would look far more natural - unless of course, this was a common behavior. For instance, you could hold a pen, or a sword, or a scepter/rod. Or you could place the hand on the hip, or a table, or behind the back or just let it hang. Notice in the first two pictures I referred to earlier: there is a sword in both of them, but in neither picture is Napoleon actually holding the prop.
I’ve also noticed in the first picture that it appears that the jacket is especially made for putting the hand in there. Which supports the theory that it is just something guys did, or they did it to warm their sword hand, or that it is particular to some social group.
As for saving work, or avoiding a tricky area. In no picture I saw (except for one I’ll mention in a minute) were both hands hidden. And the singleton hands were well executed. Hands are hard to draw, but usually a good painter will use this as an opportunity to strut his stuff, and an obvious avoidance of the area would incur criticism from his peers.
As another example of this phenomenon: Self-portrait by Gainsborough, painted in 1758 or '59. Here, one arm hangs down, and the other one is stuffed inside his vest. The picture ends just below the hand that is inside the vest. He could have only painted from the chest up if he wanted to avoid painting the hand, or couldn’t come up with another way of posing it. It seems to me like he wanted to include the hand position in the picture, because it had some significance. But it doesn’t look like it is particular to a military order, since he is not wearing a uniform. OTOH, this could also support the sword hand theory. Or that guys just did this.
I thought it had to do with reaching for a gun.
I have seen a painting of King Leopold I of Belgium with his hand tucked inside his shirt. And I THINK I saw one of Prince Albert.
A good example: Kaiser Wilhelm II, the “Kaiser” of WWI, usually has his left hand tucked inside his coat or a pocket. This was because Willy’s left arm was shorter than his right, having been wrenched out of its socket at birth, and thus rendering it useless. As Willy was an egowhore, he usually sought to hide this deformity.
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In the 18th Century portraits, it is doubtful they were reaching for a gun. Where does a gun enter into this?