Merle Haggard, George Strait and Carrie Underwood have been booked for the Las Vegas show "ACM Presents: An All-Star Salute to the Troops," CBS said. Also on the bill for the April 7 event are Florida Georgia Line, Lady Antebellum and The Band Perry. The special will be taped at the MGM Grand Garden Arena in Las Vegas. It is scheduled to air May 20 on CBS. "We are so thankful for all of the men and women in our armed forces and proud to present this fantastic night of performances in their honor," Bob Romeo, chief executive officer of the Academy of Country Music, said in a statement. "The special will be a remarkable moment in academy history and continues the 'ACM Presents' TV specials that have been so successful over the years and helps to fund the important charitable work of ACM Lifting Lives."