The Shadow Riders By - Louis L'amour

Mac Traven is on his way back home from the Civil War.  When he stops in a town, he hears that one of the Travens brothers is going to be murdered.  Mac goes to find out which brother is under attack.  He finds out they are after his brother Dal and Mac ends up saving his life.  As they continue their journey back home, they come across ranches where the women and the cattle have been taken from and the men shot.  When they finally make it back home, they find out their sister and brother have been taken and their father shot badly.  They also find out Dal's girlfriend Kate has been taken.  They go by themselves to try to save these women and stop the rampage.  They come to find out that the group is led by the Confederate Colonel Ashford.  They follow the group to Mexico where Ashford plans to trade the women for guns.  On their way there, Dal and Mac recruit help from their Uncle Jack and Brother Jesse, who escapes Ashford.  With their help, they end up attacking the enemy. At that point, Ashford had already taken Kate and some of his men to Kate's Uncle Martin's so Ashford could see if he would help.  The attack ends up being successful.  The happiness doesn't stay too long though.  It leaves when Dal realizes they still don't have Kate.  So, Jack and Jesse take the women to a town and Dal and Mac stay to free Kate.  Kate knows knows that the brothers will keep going to find her.  She just keeps thinking that "the Travens will never stop until they are free or they are dead."  To find out if they make it, you'll just have to read the book.  I thought it was pretty good.