 Pennsylvania also took steps to preserve and record the history of each regiment and unit raised in the state, as well as the muster rolls.In 1869, the official commonwealth historian Samuel Penniman Bates wrote the monumental five-volume "History of the Pennsylvania Volunteers, 1861-1865" which remains the standard reference for the commonwealth's regimental histories and unit rosters.The State Archives in Harrisburg preserves the military records of the state's emergency militia, as well as material on the state's volunteer regiments and batteries.