Marine Corps Flag
Little information is available on the flags carried by early U.S. Marines. Initially Marines may have carried the Continental Colors, also known as the Grand Union Flag. In 1776 it was considered the official flag of the American naval forces by the Maritime Committee of the Continental Congress. Although not officially recognized, this flag is considered to be the first American flag, influencing the design of the 13-star Betsy Ross flag.
In the 1830s and 1840s, Marines carried a white flag with gold fringe. It contained a depiction of an anchor and an eagle and the words "To the Shores of Tripoli." After the Mexican-American War, "To the Shores of Tripoli" was expanded to "From the Halls of Montezuma to the Shores of Tripoli."
In battles during the Mexican-American War and Civil War, field Marines carried a flag with alternating red and white stripes. An eagle perching on a shield of the United States was superimposed in the canton. A half-wreath was positioned below the shield, and 29 stars encircled the entire design.
Beginning in 1876, Marines carried the national colors (the Stars and Stripes) with "U.S. Marine Corps" embroidered in yellow on the middle red stripe.
Here's some of the flags on display during the march.
Here's my interpretation of the U.S. Marine flag based on the description above.
Note that my marines are wearing the summer cotton uniform.
Based on additional research, the regular Marine uniform may have been green with
white leathers, so may have to paint some up in those colors as well.