This manual serves as a guide for the Philippine Army functional staff offices, Philippine Army major units (PAMUs), and ground units in identifying, sharing, and archiving lessons-learned gathered from the different units performing maneuver, maneuver support, and sustainment operations. It sets up a lessons-learned system from key concepts, provides a structure for the organization, as well as the necessary tools for the system to be piloted. Lessons-learned is a key aspect of any organization. It is an acknowledgement that mistakes have been made and that the organization is making strides to be better. Lessons-learned system is also a celebration of best practices in an organization’s operations. The Philippine Army, while making great strides towards modernization, is aptly anchored on the realities of its ground operations. In making this manual, the organization embraces its flaws and commits to rapidly and effectively correct errors and eventually improve them. Thus, it is envisioned that the Philippine Army Major Units (PAMUs) widely make use of this manual in documenting and sharing lessons learned in their respective level of command, and to higher authority as necessary, to effectively fulfill the Army’s mandate and uphold its duty to the Filipino people. The proponent of this manual is the Operations Research Center, Philippine Army. However, Doctrine and Capability Integration Center, TRADOC, PA is responsible for the review and updating of this publication. Send comments or recommendations to the Commander, TRADOC, PA, Camp O’Donnell, Capas, Tarlac Attn: Director, DACIC) or via email at dcannex45@gmail.com and via website at doctrinecenterpa.com. Feedbacks to this publication are also welcome telephonically via the Bonifacio Telephone Exchange trunk line number 845-9555 or military local line number 7650 extension 4971.