Joseph Arnold Weydemeyer (February 2, 1818 – August 26, 1866) was a military officer in the Kingdom of Prussia and the United States as well as a journalist, politician and Marxist revolutionary.

At first a supporter of "true socialism", Weydemeyer became in 1845–1846 a follower of Karl Marx and Friedrich Engels and a member of the League of Communists, heading its Frankfurt chapter from 1849 to 1851.

The Eighteenth Brumaire of Louis Napoleon, written by Marx, was published in 1852 in Die Revolution, a German-language monthly magazine in New York established by Weydemeyer.

He began to read the bourgeois radical and socialist newspaper Rheinische Zeitung, the Cologne paper Marx became editor and which was suppressed by Prussian censorship in 1843.

In the Minden garrison, the paper inspired revolutionaries like Fritz Anneke, August Willich, Hermann Korff, and Friedrich von Beust, all of whom, like Weydemeyer, will become prominent Forty-Eighters and after that officers of the Union army in the Civil War.

At the same time, he made a career as a construction engineer for the Cologne–Minden Railroad, but he quit the job soon after the beginning in 1848 because the company ordered its employees to stay out of political demonstration.

But in 1849, the counter-revolution succeeded and the Prussian absolutism crushed the Frankfurt Parliament, the armed democracy in Baden and the Electorate of the Palatinate and all the democratic papers.

In spring 1852, Weydemeyer brought out Marx's Eighteenth Brumaire of Louis Bonaparte as a final number of Die Revolution, after arranging for serial publication of Engels The Peasant War in Germany in the New York Turn-Zeitung between January 1852 and February 1853.

In the July number of Turn-Zeitung, he began a discussion of American labor issues and the free trade versus protection debate, where he took a traditional Marxist stand for the industrial development.

In the Turn-Zeitung of November 15, Weydemeyer wrote a review of the election campaign of 1852, pointing the absence of labor issues in the platforms of the Whig and Democratic parties.

This was an organization of mixed union and party functions, and presented a program of immediate issues for the working class and the socialist goal at the same time.

The program was for immediate naturalization of all immigrants who wished to gain American citizenship, it favored federal, rather than state, labor legislation, stood for guaranteed payment of wages to workers whose employers went bankrupt, assumption by government of all costs of litigation with free choice of counsel, reducing the working day to ten hours, banning labor for children under sixteen, compulsory education with government maintenance for children whose families were too poor, against all Sunday and temperance laws, for the formation of tuition-colleges and for state acquisition of existing private colleges, for keeping the national lands on the frontier inalienable, etc.

The American Workers League functioned for several years under a central committee made up of delegates from wards clubs and trade unions.

When in the context of the Know-Nothing agitation, in 1855, the members began forming a secret military organization to defend themselves against nativist attacks, Weydemeyer withdrew from the League.

William Sylvis, leading native-born trade unionist, didn't engage in Republican politics, but showed approval for their platform in several commentaries published by Die Welt.

According to his Marxist opinion against the parceling out of government lands to small farmers, Weydemeyer denounced the Homestead Act agitation in 1854 as contrary to the interest of the workers and was in favor of large-scale agriculture.

Shortly after dropping the American Workers League, Weydemeyer left New York and settled down in the Midwest, where he lived for four years, first in Milwaukee and then in Chicago, where he worked as a journalist and also as a surveyor.

Thanks to his background as a Prussian military officer and surveyor, he became a technical aide on the staff of General John C. Frémont, the commander of the department of the West.

The same day William S. Sylvis inaugurated the National Labor Union in Baltimore, Weydemeyer died of cholera in St. Louis, Missouri, at the age of 48.