Most clansmen wore a shirt, known as a leine, and a plaid (blanket) of multicoloured woolen material.
The Plaid
The plaid could be four yards long. It was folded into pleats on the ground before the wearer lay on it and pulled it around him, securing it around the waist with a belt. The result was a garment that covered the body from knees to head.
This was known as a feilidh-mor, or great kilt, and suited the icy conditions of the highlands perfectly. In winter, highlanders forced to spend a night in the open allegedly dipped the plaid in water before wrapping it around their bodies. One of the chief advantages of wearing wool is it's ability to retain heat even when wet. The outside of the plaid would freeze, leaving the wearer cocooned within a steamy sort of warmth.
The plaid had it's drawbacks. For one thing, it was very bulky. In battle, warriors would often discard their plaids and charge the enemy naked from the waist down. A solution to this was found with the introduction of the philabeg (little kilt), probably sometime in the late 1600's. This form of kilt is the one most familiar to us today.
Many eighteenth century highlanders wore tight-fitting tartan trousers known as trews. These were usually gartered below the knee. Checked socks, a bonnet (beret) on the head, and a pair of brogues for the feet completed the outfit.
Tartan
The wearing of brightly coloured checked material was a longstanding celtic custom. Ironically, clan tartans were a Victorian innovation. Highlanders of the eighteenth century just loved bright colours and one man alone would often sport tartans of several different colour schemes.
Highland Weapons
The most popular sword was the basket-hilted broadsword. It was called a claymore, from the gaelic Claideamh Mhor (great cleaver). It should not be confused with the medieval two-handed sword of the same name. The restrictive hilt enclosed the entire fist and meant that the broadsword was best suited to hacking attacks.
On his left arm, the highlander would carry a targe, a small circular shield of leather covered wood. A long spike was screwed into the centre, and this turned the targe into an offensive weapon. The targe was gripped by flexible leather straps which were soft enough to enable the wielder to hold a dirk (dagger) in his left hand.
Most highlanders owned a musket and/or several pistols. Usual procedure in battle was to fling themselves at the enemy in a wild ferocious charge - another very celtic characteristic. The highlander would fire his musket befoe discarding it. Next, he would fire his pistols: many scottish pistols had solid iron or steel butts, and once fired, they would be hurled at the enemy with potentially devestating effect. At the last, the clansman would heft his dirk, sword and targe before closing with the enemy for hand to hand combat, where most battles were decided.
Sources:
Glencoe, John Prebble (Penguin, 1966)