Yes he did. There are compilations of his writings on colonialism and on the USA:
* https://drive.google.com/file/d/0B1ZP6ZurgOg-blRnUnAxR0VBSm8/view
* https://archive.org/details/MarxandEngelsontheUnitedStates
I'll also quote something I wrote elsewhere:
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The labor historian Philip S. Foner on the first Marxist group in the USA, founded in 1857:
>The Communist Club of New York was not only the first Marxist organization in the Western Hemisphere; it was the only socialist (and labor) organization that invited blacks to join as equal members. Its constitution required all members to "recognize the complete equality of all persons—no matter of whatever color or sex." The club was also in the forefront of the struggle against slavery, and its members played an important role in mobilizing the German-American workers in opposition to the "peculiar institution." ....
>By 1860, these workers had become committed to a radical antislavery position. Moreover, men like Weydemeyer, Douai, and members of the Communist Club, including Sorge, formed a significant force in the Republican Party, seeking to push the party in a more radical direction, particularly in the direction of favoring the total abolition of slavery.
>When the Civil War began with the attack on Fort Sumter, most of the German radical organizations disbanded because the majority of their members enlisted in the Union forces. The New York Communist Club did not meet for the duration of the war since most of its members had joined the Union army.
Besides mere advocacy and campaigning, Joseph Weydemeyer and Adolph Douai had a more direct influence. A conference was held at the Deutsches Haus in Chicago in May 1860. This was a meeting of German-American representatives from around the country who hoped to influence the proceedings of the Republican National Convention which would be held days later in the same city. Both men were sent to the conference and Douai was one of two participants tasked with preparing resolutions to be presented to the Convention on behalf of German-Americans. The proceedings of the conference worried the Convention's organizers, who feared the Republicans losing the large German-American vote in various states. As a result the conference had an important (some say decisive) impact on the Convention's decision to nominate Lincoln as the Republican Presidential candidate owing to his strong ties to that community.
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