Per the West Virginia Archives and History link provided
“The Battle Of Fairmont
Three Hours Desperate Fighting!
300 Unionists Against 6,000 Rebels.
Fairmont, Va., May 4, 1863.”
It was a rebel raid but seems consensus is a short battle? The battle flag of the 106th Also has Fairmont on it but it looks like alt. spelling
Good answer because the word Rebel Raid is used in conjunction with battle for this event
Edit: fixed typos