During the 1840s, Bowser painted banners for a diverse range of clients, including the
Know Nothing Party, and received a commission to paint the portrait of prominent abolitionist and real estate developer
Jacob C. White. Active in that decade's efforts to repeal the clause in
Pennsylvania's Constitution which prohibited blacks from voting, Bowser and his family also became so involved with the
abolition movement that their home became a stop on the
Underground Railroad. In 1858, politics and advocacy merged with art when Bower painted the portrait of abolitionist
John Brown while Brown was visiting the Bowser home. During this same period, Bowser also completed work on his painting,
The Firebell in the Night. During the
American Civil War, Bowser joined with several other prominent members of Philadelphia's African-American community to begin recruiting soldiers in 1862 in the event that the federal government would permit large numbers of black soldiers to enlist following the 1863 announcement of the
Emancipation Proclamation by
President Abraham Lincoln. Bowser was then commissioned in early 1863 to design banners and battle flags for eleven of those African-American regiments in preparation for their respective mustering at
Camp William Penn, which was located just outside of Philadelphia. 's printed
broadside, recruiting men of color to enlist in the U.S. military after the
Emancipation Proclamation. Bowser's work on the first banner was paid for through a commission awarded by the
Contraband Relief Association (CRA), an organization headed by
Elizabeth Keckley, the formerly enslaved woman who became
Mary Todd Lincoln's dressmaker. It was then presented by the CRA to the leaders of
1st United States Colored Infantry. With respect to the other Bowser-designed battle flags, historians at the Pennsylvania Historical and Museum Commission note that: Another event on July 6 filled Philadelphia's National Hall with a standing room only crowd. According to Philadelphia's
Press, a "great many persons in the audience were white, and they all seemed to take a lively interest in the proceedings." The first orator, the Hon. William D. Kelley, began by announcing, "the rebel army of Virginia is no more," that Virginia was "henceforth secured to freedom," and would "no longer lead blue-eyed girls or stalwart black men to the slave mart." Repeatedly interrupted by loud cheers, Kelley "then asked the black men to stop blacking boots ... to engage in the glorious work of war," adding that he "would not have it said of all the colored regiments of Pennsylvania that there were no Philadelphians in it." He was followed by abolitionist and orator
Anna Elizabeth Dickinson. Enumerating the Union's recent losses and victories, she told the crowd: "If the North succeeds — if the Union succeeds, it will be by letting all men fight for the stars and stripes. This war is not for the white men or the colored men, or for the flag, or for a military victory, but it is a war of democracy against aristocracy, a war of liberty against slavery." A lengthy resolution by Professor E. D. Bassett proclaimed, "Men of color, to arms, now or never!", and described their present era as "a golden moment."
Frederick Douglass also rose to speak, and also gave a lengthy address in which he reflected on his life during and after his enslavement and stressed the urgent need for black men to fill up new regiments "for the purpose of upholding the stars and stripes, and crushing out the rebellion of the slaveholders." Following a brief poetry reading and musical performance by a concert band, the membership elected a slate of officers, which included the naming of Bowser as one of several vice presidents.. Although Brown died in 1859, the two met at Bowser's
Underground Railroad safehouse. In 1865, Bowser also painted a portrait of Lincoln, working from an image of the president that was later used to create America's post-Civil War five-dollar bill. . ==Post-war life==