According to Museum of the Confederacy Director John Coski, Miles' design was inspired by one of the many "secessionist flags" flown at the
South Carolina secession convention in
Charleston of December 1860. That flag was a blue
St George's Cross (an upright or Latin cross) on a red field, with 15 white stars on the cross, representing the slave-holding states, and, on the red field, palmetto and crescent symbols. Miles received various feedback on this design,
including a critique from Charles Moise, a self-described "Southerner of Jewish persuasion." Moise liked the design but asked that "... the symbol of a particular religion not be made the symbol of the nation." Taking this into account, Miles changed his flag, removing the palmetto and crescent, and substituting a heraldic
saltire ("X") for the upright cross. The number of stars was changed several times as well. He described these changes and his reasons for making them in early 1861. The diagonal cross was preferable, he wrote, because "it avoided the religious objection about the cross (
from the Jews and many Protestant sects), because it did not stand out so conspicuously as if the cross had been placed upright thus."