That was part of the need for the Conscription law was that the 12 month enlistments were about to expire. They (both north and South) had the same situation 3 years later in the winter and spring of 1864. It is also one of the reasons so many of the 12 month enlistees from Arkansas and those wounded at the Battle of Shiloh in Fagan's 1st Arkansas returned home to Arkansas before re-enlisting to continue their fight west of the Mississippi.