Historical Guns and Related Injuries

http://en.wikipedia.org/wiki/History_of_firearms

Potted version

Ignoring "fire-lances" (pots filled with burning stuff stuck on poles and acting like primitive flamethrowers) the first thing we'd recognise as a "gun" was the cannon. Miniature versions of cannon would be attached to wooden stocks and braced at the hip, leaving one hand free to apply fire to the touch-hole.

The invention that revolutionised firearms was the match-lock. The slow match was invented - a rope impregnated with gunpowder that burns slowly - and clipped into a lever mechanism that dips the burning match into a pan filled with gunpowder to the side of the barrel, with a little hole allowing the flame to pass through and ignite the main charge.

This method allowed the gunner to hold the gun with both hands, allowing better aiming, though matchlock muskets were still horribly inaccurate - lots of smoke and noise, but often precious little damage. They were also rubbish in wet weather, when the slow match got wet. This led to the invention of flint-lock muskets, which kept a lid on the priming pan and struck a spark from a falling flint. Better, but still not ideal and still producing a lot of smoke.

Muskets were used alongside crossbows and bows for centuries, as all of them had their own advantages and disadvantages. Primarily, the advantage of the musket was that it could be used effectively by relatively unskilled troops, while good bowmen took generations to mature and good crossbowmen required a certain amount of manual strength. Also, they could be mass-produced rather easier. The disadvantage was - aside from inaccuracy and the propensity to injure or kill the user if something went wrong - muskets were very slow to reload.

So in the time period you're talking about, as handguns are just coming into warfare, it's likely that battle tactics and the like won't have changed that much to accommodate them. They'll be used in a scattered manner, since there won't be many of them around, and will probably frighten the bejeesus out of raw recruits and feudal levies. Once they start to be used in any sort of numbers, the battlefield suddenly gets a lot smokier - great palls of white smoke drifting everywhere. In fact, in some cases, massed musketry was used as much as a way of laying down a smokescreen for a charge with cold steel as it was to actually attempt to injure the enemy.

If you can fly a Sopwith Camel, you can fly anything.

Early firearms, (matchlock muskets for instance) were slow to reload, so they were often deployed in large formations, with units of spearmen or pikemen to protect them. The guns were heavy, not particularly accurate or reliable, and they used black powder-type gunpowder (not the smokeless powder of today), so after firing they produced large clouds of smoke. They could be made useless by rain, snow or other damp weather. But it was easier to train a rifleman than an archer, so it was easier to create a large army of riflemen, or arm conscripts.

In the short-term, they were not accepted quickly, but in the long term they were very quickly accepted indeed and grew to be the dominant weapon in only a few centuries. Wikipedia has a decent article on the subject:

http://en.wikipedia.org/wiki/Gunpowder_warfare

It could be anywhere from the 15th to the 18th century, if firearms and melee weapons are used equally. Medical knowledge was sadly lacking, no antiseptic for instance. Good knowledge of bone-setting, though. They could splint a broken limb no problem, but if you had a penetrating injury to the torso, you were most likely buggered.

Favourite gun myths.

1) Bullets knock people down. No, really.
2) .45 ACP is the only pistol round worth using. No question.
3) .50 BMG is illegal for use in warfare against people, but not materiel. Truth.

I would like to supplement that said by the previous two posters. Some good info there, so I'll try not to repeat it. I have never heard of muskets being used to lay down smokescreens... that is most likely apochryphal.

In the period I think you are trying to replicate, armies consisted of large blocks of musketeers / aquebusiers protected by large blocks of pikemen. Cavalry was still a significant combat force; it tried to find an oppoortunity to charge the gunners while they were reloading. The pikemen's primary job was to protect the gunners from the cavalry. So the cavalry would run around the flanks of the battle, trying not to get shot, and looking for an opportunity to charge in. As the accuracy of firearms increased, this techique became less viable.

Here's a good article on this type of warfare: http://en.wikipedia.org/wiki/Pike_and_shot

You mentioned swords specifically; if you want swords, the best unit to model them after, IMHO are the German "Landsknechts." They sometimes wielded large "Zweihander" swords, and their mission was to assault the pike formations and disrupt them. The historical record is unclear just how much success they had at this.

http://en.wikipedia.org/wiki/Landsknecht

As for battlefield medicine of the time, there was not much at all. As has been said, setting bones is about as technical as it gets. Perhaps a trepannation of the skull in cases of concussion. But no drugs, no real surgical tools as we know them today.