Short answers, pulled from the story.
Governor Thomas Overton Moore ordered militia to seize the U.S. arsenal at Baton Rouge on the 8th of January 1861. He also directed troops to occupy Fort Jackson and Fort St. Philip guarding New Orleans.
Union forces took control of New Orleans on the 25th of April 1862. The government designated areas under its control as a state within the Union because many residents held Union sympathies or compatible commercial interests.
Antebellum Louisianans P.G.T. Beauregard, Braxton Bragg, and Richard Taylor commanded significant independent armies during the conflict. Harry T. Hays and Chatham Roberdeau Wheat led notable brigades including the celebrated Louisiana Tigers.
Full restoration to the United States occurred for Louisiana on the 9th of July 1868. The state met Reconstruction requirements by ratifying constitutional amendments abolishing slavery and granting citizenship to former slaves.
Military engagements in Louisiana concentrated heavily along major waterways like the Red River Campaign. Fighting occurred at Donaldsonville, Georgia Landing, Fort Bisland, Irish Bend, Vermilion Bayou, Plains Store, Port Hudson, Milliken's Bend, LaFourche Crossing, Goodrich's Landing, Kock's Plantation, Stirling's Plantation, Bayou Bourbeux, Henderson's Hill, Mansfield, Pleasant Hill, Blair's Landing, Monett's Ferry, Calcasieu Pass, Yellow Bayou, and Mansura rounds.