The second-most commonly-seen image is the statue that stands in the United States Capitol, one of two statues representing the Commonwealth of Pennsylvania. This statue, which was created in 1889 by Blanche Nevin, hardly resembles the Martin Gallery portrait, though it is possible to imagine similarities. It depicts Muhlenberg as the new colonel of the 8th Virginia Regiment, removing his pastor’s robe to reveal a military uniform. (Muhlenberg was made a general after serving as the regiment's colonel for about a year.)
Directly upstairs from that statue, in the Capitol Rotunda, there is another image of Muhlenberg which may be the most reliable. It is a partially-obscured side image of General Muhlenberg in John Trumbull’s grand depiction of The Surrender of Lord Cornwallis. According to the Architect of the Capitol, Trumbull created this giant painting “between 1819 and 1820, basing it upon a small painting … that he had first envisioned in 1785…. In 1787 he made preliminary drawings for the small painting. Although he struggled for a time with the arrangement of the figures, he had settled upon a composition by 1788.”
Trumbull worked hard to make his depiction of the people in his history paintings as accurate as possible. He wrote that “to transmit to their descendants, the personal resemblance of those who have been the great actors in those illustrious scenes” was one of the goals of his patriotic painting. A war veteran from a prominent Connecticut family, Trumbull knew many of his subjects personally.
“To create portraits from life of the people depicted in this and other paintings," the Capitol architect's website says, "Trumbull traveled extensively. He obtained sittings with numerous individuals in Paris (including French officers at Thomas Jefferson’s house) and in New York. In 1791 he was at Yorktown and sketched the site of the British surrender. He continued to work on the small painting during the following years but did not [immediately] complete it; nevertheless, in January 1817 he showed it and other works in Washington, D.C., and was given a commission to create four monumental history paintings for the Capitol. Surrender of Lord Cornwallis was the second of these large paintings that he completed. He exhibited it in New York City, Boston, and Baltimore before delivering it to the United States Capitol in late 1820. He completed the small painting around 1828; it is now part of the collection of the Yale University Art Gallery.”
If he even needed a sitting, Muhlenberg would not have been a hard man for Trumbull to find. The retired general served in Congress and as vice president and de-facto governor of Pennsylvania during the earlier years of Trumbull’s project. Though Trumbull’s portrait should be considered the most reliable, it is worth taking a moment to compare the Trumbull side-image to the anonymous portrait at Muhlenberg College. They are quite similar. In both depictions he has a long nose, slightly angled eyes, and slightly jowly cheeks. If the college has not made an effort to research the origin of the portrait in its collection, it should.