One of the most interesting medieval mercenary groups was the White Company, immortalized in the novel of the same name by Sir Arthur Conan Doyle. Active in continental Europe (including France and Italy) in the mid 1300s, they were well known both for their brutality and their combat effectiveness.

For the most part, they seem to have been English veterans of the Hundred Years War, with the notable exception of their German captain-general, Albert Sterz. Sterz was eventually eclipsed by the legendary English mercenary, John Hawkwood. Estimates of their initial size upon their initial entry into Italy in 1361 vary, but they seem to have numbered somewhere between two and five thousand men.

Like contemporary English armies, the White Company rode to battle but fought dismounted, with longbow archers supported by men-at-arms. Unlike regular English troops under the command of the crown, the White Company seems to have had far less longbowmen available and supplemented the ranks of their archers by absorbing bands of Hungarian mercenaries present in Italy. They were notably skilled in capturing towns and fortresses as well as on open battlefields.

After entering Italy in 1361, the Company entered into the service of the city of Pisa in 1363. Later that year, the Pisans went so far as to dismiss all other forces in their service, making the White Company their sole military force. It is at this time that John Hawkwood became the leader of the Company. The impact this had on Albert Sterz, the original captain, is unknown. Following a largely unsuccessful campaign against Florence in 1364, most of the Company succumbed to bribes from the Florentines and deserted Pisan service. Hawkwood remained loyal to Pisa and thus split from the White Company.

While fighting for the Florentines, the White Company became entangled in a feud with a German mercenary company. Over the next few years, the feud devolved into open combat, which the Company received the worst of. The final defeat was at the Battle of San Mariano in 1365, where the Company was forced to surrender completely to the Germans. Most of the footsoldiers were released shortly after, but many of its leaders were only released several years later.

After this defeat, the White Company was essentially dissolved. The membership was largely absorbed into the mercenary band of John Hawkwood. This successor force is sometimes called the White Company, but this is a label applied by modern historians, and contemporary sources refer to Hawkwood's new force as merely being "English companies" rather than the White Company.

Source: "The Fox and the Lion: The White Company and the Hundred Years War in Italy," by William Caferro. This essay can be found in The Hundred Years War: A Wider Focus, edited by Andrew Villalon and Donald Kagay.