At 6 A.M. on October 25th, 1854, in the British picket post just outside the town of Kamara, at the eastern end of the Allie's right of line in the Crimea, drowsy sentries noticed belatedly through morning mists that the vanguard of the Russian Army was coming calling. As a two-pronged Russian cavalry attack enveloped their outposts, they fired their few cannons, spiked their guns, and beat a hasty retreat to stronger positions, and thus was the Battle of Balaclava begun.
In a campaign marked by notable clumsiness on both sides, the Russian army overran four separate British outposts, manned by Ottoman Turk troops, each supported by a contingent of British guns.
After a cavalry charge by the British Heavy Brigade sent the Russians temporarily reeling, a vague order from a distant commander, delivered and poorly articulated by a blockheaded (also a helpfully but too late short-lived) staff officer sent the Light Brigade of British cavalry charging headlong down a valley between ranks of Russian artillery and infantry on both sides, and into the mouth of Russian artillery and cavalry at the end.
Despite suffering frightful casualties, the Light Brigade reached its objective, and briefly routed the Russian artillerymen and cavalry, only to find that it had been abandoned by the supporting Heavy Brigade, and now had to retreat along the same line, between the bloodied but regrouping Russians that had so pummeled its ranks on the way in.
As they returned to friendly lines after running the gauntlet of fire both ways, of the 666 men (lucky number) who had begun the Charge Of The Light Brigade, 110 were killed, 129 wounded, 32 wounded and captured by the Russians, and 375 horses killed, leaving the brigade at effectively half-strength, and ending further festivities on the field of battle for the rest of the day, and spawning endless films and poetry in commemoration of epic stupidity in war, boldly displayed.
The lines of the Allied siege around the Black Sea port of Sevastopol hardened, and ultimately, after a long and horrible campaign, the Allies prevailed, forcing the Russians to sue for peace after 3 years of war had wearied both sides.
The entire affair, bolstered by religious claims, was essentially 19th century geopolitics, with Britain and France supporting the Ottoman Empire in efforts to contain Russian imperial moves from the Holy Land to as far north as the modern Czech Republic. (Plus ca change, etc. ...)
With the town of Balaclava nearby, and British forces overall commanded by Baron Raglan, and the Light Brigade commanded by Lord Cardigan, the major contribution - owing to a bitter winter siege - was a lot of knitted woolen wear, and due to the heretofore medieval methods of battlefield medical care, the pioneering efforts of establishing modern nursing, courtesy of Florence Nightingale.
Other newfangled innovations were the first notable appearance of trench warfare, railroads, rapid telegraphic communication from capitol and HQ to front line commanders, the rise of war correspondent press and photography, the use of indirect-fire artillery, and rifled muskets using the accurate Minie ball. It also saw the end of the Russian medieval serfdom conscription, the British institution of the Victoria Cross award, and like all wars, considerable innovation in medicine: not only the already-mentioned professional transformation of nursing, but the introduction of medical triage, anesthesia in surgery, use of plaster casts, and better amputation techniques, all coming just as medicine started to grasp the real-world implications of Pasteur's Germ Theory on everyday medical practice.
All, happily, just in time for the backwards practitioners of the military and medical arts in the United States to re-learn all the exact same lessons a few short years later, starting in the spring of 1861, outside Manassas, VA, in an epic multi-year bout of carnage hitherto unseen in the hemisphere.
Just in case anyone thought a balaclava was just about a winter cap.