Question: What year did the infantry regiment featured in the 2006 film "Only the Brave" begin?

<P0-S0> The 39th Arkansas Infantry Regiment or Cocke's Arkansas Infantry Regiment (also known as "Johnson's regiment," "Hawthorn's regiment," "Cocke's regiment," and "Polk's regiment") was an infantry formation in the Confederate States Army during the Civil War, and was successively commanded by Colonels A. W. Johnson, A. T. Hawthorn, J. B. Cocke, and Lieutenant-Colonel C. Polk. <P0-S1>  It was mustered into service on June 17, 1862, at Trenton, Arkansas, remaining active through May 26, 1865. <P0-S2>  When Major-General Sterling Price's staff decided to designate all infantry regiments in the District of Arkansas as "Trans-Mississippi rifle regiments", the 39th Arkansas Infantry Regiment was designated as the 6th Trans-Mississippi Rifle Regiment. <P0-S3>  One other Arkansas regiment was designated as the 39th Arkansas Infantry; that regiment being successively commanded by Colonels Hart, McNeill, and Rogan. <P0-S4>  It was originally designated as the 39th Arkansas, but later redesignated as the 30th Arkansas Infantry Regiment. <P0-S5>  The 39th served in the Trans-Mississippi Theater of the American Civil War and participated in all of the principal engagements in that department before disbanding on May 26, 1865. <SEP> <P1-S0> The 18th Arkansas Infantry (Marmaduke's) (1861–1865) was a Confederate Army infantry regiment during the American Civil War. <P1-S1>  The unit was also briefly identified as the 1st Arkansas Infantry Battalion. <P1-S2>  The unit was most often referred to as the 3rd Confederate Infantry Regiment. <P1-S3>  The designation "Confederate Infantry Regiment" was intended to convey the difference between Provisional Confederate Army units and Regular Confederate Army Units, with Provisional units being those regiments who received a state designation such as "XX Arkansas Infantry Regiment". <P1-S4>  In practice, the designation was most often utilized when Regiments were assembled utilizing companies from more than one confederate state. <P1-S5>  The "3rd Confederate Infantry Regiment" is occasionally misidentified as the 3rd Arkansas Infantry Regiment commanded by Colonel Van H. Manning. <SEP> <P2-S0>  The film, produced and directed by Lane Nishikawa is a fictionalized account of the rescue of the Lost Battalion. <P2-S1> Only the Brave is a 2006 independent film about the 100th Infantry Battalion/442nd Regimental Combat Team, a segregated World War II fighting unit primarily made up of "Nisei" Japanese Americans, which for its size and length of service became the most decorated unit in U.S. military history. <SEP> <P3-S0> The 442nd Regimental Combat Team is an infantry regiment of the United States Army, part of the Army Reserve. <P3-S1>  The regiment was a fighting unit composed almost entirely of American soldiers of Japanese ancestry (mostly from Hawaii) who fought in World War II. <P3-S2>  Beginning in 1944, the regiment fought primarily in Europe during World War II, in particular Italy, southern France, and Germany. <P3-S3>  Most of the families of mainland Japanese Americans were confined to internment camps in the United States interior.