the 880th was an organic unit of the 69th Infantry Division, meaning they were a permanant divisional unit always under command & control of the division Headquarters. Every infantry division was made of many units, ie: 3 infantry regiments, HQ Company, an Engineer Combat Battalion, Medical Detachment, Quartermaster company...etc, and they had 4 artillery battalions, 3 Light Field Artillery Battalions which were 105MM howitzers & 1 Medium Field Artillery Battalion with 155mm howitzers.
These 4 field artillery battalions main job was to support the operations of the division`s infantry regiments.
The 3 Light Field Artillery Battalions (105mm) of the 69th INF Div were the 879th FA Bn, The 880th FA Bn and The 881st FA Bn; The Medium Field Artillery Battalion (155mm) was the 724th Medium F A Bn