Development of soldier systems for the 21st century Land Warrior is exemplified by the techniques used on the Integrated Sight (IS) Program to integrate a thermal imager, a CCD camera, a miniature laser rangefinder (LRF), an electronic compass, and an infrared (IR) pointer into an advanced weapon sight and surveillance system. The Integrated Sight is being developed as a technology demonstrator and potential future upgrade to the Land Warrior and Thermal Weapon Sight Programs. A key integration challenge involves initial mechanical boresight alignment of the subsystems as well as boresighting of the thermal sight, CCD camera, LRF, compass, and IR pointer to each other in the IS system, and to the various weapons in the inventory. One aiming procedure requires the soldier to place a reticle on a target and fire the LRF. The IS then computes the ballistic trajectory based on the target range and the selected round, and displaces the reticle to a new aiming point to compensate for the calculated ballistic drop. For this concept to meet requirements, boresight tolerances must be carefully selected and the design of the weapon sight must be robust enough to withstand the rigors of use and the hostile shock and vibration of weapon firing.