Three of the 1st Infantry Division's five brigades cased their colors ahead of deployments to several regions Jan. 15 at Fort Riley.About 3,500 1st Armored Brigade Combat Team Soldiers will soon depart to serve a nine-month mission in support of Atlantic Resolve. They are to replace the 1st Armored Brigade Combat Team, 1st Cavalry Division, from Fort Hood, Texas.About 1,900 1st Combat Aviation Soldiers will deploy to Europe in support of Atlantic Resolve and to Afghanistan in support of Operation Freedom's Sentinel. Those serving in Europe will replace troops from the Combat Aviation Brigade, 4th Infantry Division, who will return to Fort Carson, Colorado.About 150 1st Inf. Div. Sust. Bde. headquarters Soldiers will replace the 101st Airborne Division Sustainment Brigade from Fort Campbell, Kentucky, in Afghanistan in support of Operation Freedom's Sentinel."Each brigade has trained hard to prepare for these missions and is ready for the challenges that lay ahead," said Maj. Gen. John Kolasheski, 1st Inf. Div. and Fort Riley commanding general.Units deploying to Europe will fall under the Mission Command Element (Provisional), which is led by Col. Patrick R. Michaelis, who serves as the element's highest-ranking officer. Soldiers from the "Big Red One" headquarters are also deployed as part of the MCE. When at Fort Riley, Michaelis is the 1st Inf. Div. deputy commanding officer for maneuver.Atlantic Resolve is a mission Fort Riley knows well, Kolasheski said.Atlantic Resolve's goal is to build readiness in rotational units, provide strategic reassurance to allies and improve multinational interoperability and deter aggression throughout Eastern Europe, Kolasheski said. Soldiers will engage in training events in Bulgaria, Estonia, Hungary, Latvia, Lithuania, Poland and Romania, according to information from the division."First ABCT and 1st CAB will now take the lead in those efforts," the general said.Soldiers of the 1st Inf. Div. Sust. Bde. and 1st CAB's 1st Attack Reconnaissance Battalion, 1st Aviation Regiment, will support forces in Afghanistan -- "those who are continuing our mission to advise and assist Afghan forces, ensuring they are positioned to remain strong, trained and are continually building capacity and capacity to execute security operations in their home country," Kolasheski said.