During the Italian Risorgimento, the volunteers that followed Garibaldi in southern Italy were called Redshirts (Camicie rosse) because of their shirts (complete uniforms were beyond the finances of the italian patriots); they were also called i Mille, because they were roughly one thousand (in italian: Mille).

During his years of exile, Garibaldi spent time in heroic military action in Uruguay and in private retirement in New York City. Both places have been claimed as the birthplace of the Garibaldian red shirt.

The formation of his force of volunteers in Uruguay, his mastery of the techniques of guerilla warfare, his opposition to the Emperor of Brazil and Argentine territorial ambitions perceived by liberals as imperialist too, and his victories in the battles of Cerro and Sant'Antonio in 1846 that assured the independence of Uruguay, made Garibaldi and his followers heroes in Italy and Europe. Garibaldi was later hailed as the 'Hero of Two Worlds' on the basis of these exploits.

In Uruguay, calling on the Italians of Montevideo, Garibaldi formed the Italian Legion in 1843. In later years it was claimed that in Uruguay the legion first sported the red shirts associated with Garibaldi's 'Thousand', which were said to have been obtained from a factory in Montevideo which had intended to export them to the slaughter houses of Argentina. Red shirts sported by Argentinian butchers in the 1840s are not otherwise documented. And the famous camicie rosse did not appear during Garibaldi's efforts in Rome in 1849-50.

Later, after the failure of the campaign for Rome, Garibaldi spent a few years, ca 1850-53, with the Italian patriot and inventor, Antonio Meucci, in a modest gothic frame house (now designated a New York City Landmark), on Staten Island, New York City, before sailing for Italy in 1853. There is a Garibaldi museum on Staten Island, New York.

In New York, during the pre-Civil War era, rival companies of volunteer firemen were the great working-class heroes of the city. Their courage, their civic spirit and the lively comradeship they demonstrated inspired fanatic followers throughout New York, the original 'Buffs'.

Volunteer fire companies varied in the completeness and details of their uniforms, but they all wore the red flannel shirt. When Garibaldi returned to Italy after his New York stay, the red shirts made their first appearance among his followers.

Garibaldi remained a local hero among European immigrants back in New York. The 'Garibaldi Guard' of the 39th New York State Volunteers fought in the American Civil War, 1861-65. As part of their uniform they wore red woolen 'Garibaldi Shirts,' at least all enlisted men did. The New York Tribune sized them up:

The officers of the Guard are men who have held important commands in the Hungarian, Italian, and German revolutionary armies. Many of them were in the Sardinian and French armies in the Crimea and in Algeria.

A rather famous picture of Captain Charles Schwab shows him wearing a red woolen, undecorated shirt with a left breast pocket.