A novel class of piezoelectric-based energy harvesting devices with integrated safety and firing setback event detection electronics and logic circuitry that can be used in gun-fired munitions is presented. In this paper, the application of the device to the development of initiators for thermal reserve batteries in gun-fire munitions is presented. The novel and highly efficient electrical energy collection and storage and event detection and safety electronics used allows the use of a very small piezoelectric element. As a result, such devices can be highly miniaturized for used in small reserve batteries. For thermal battery initiation, when the prescribed firing setback acceleration profile, i.e., the prescribed all-fire condition is detected, a highly efficient charge collection electronic circuitry routes the charges generated by the piezoelectric element of the device to the initiator bridge element, thereby causing the thermal battery pyrotechnic material to be ignited. For munitions powered by thermal reserve batteries, the present initiation device provides a self-powered initiator with full no-fire safety circuitry for protection against accidental drops, transportation vibration, and other similar low amplitude accelerations and/or high amplitude but short duration acceleration events. The device is shown to be readily set to initiate thermal batteries under almost any all-fire conditions. The device can be readily hardened to withstand very high G firing setback accelerations in excess of 100,000 G and the harsh firing environment. The design of prototypes and testing under realistic conditions are presented.