Original: The Confederate States Army was the army of the Confederate States of America (or "Confederacy") while the Confederacy existed during the American Civil War. On February 8, 1861, delegates from the seven Deep South states which had already declared their secession from the United States of America adopted the Provisional Constitution of the Confederate States of America.
Simplified: The Confederate States Army (GSA) was organized in February 1861 to defend the newly formed Confederate States of America from military action by the United States government during the American Civil War.