A pile group consisting of four cast-in-place concrete piles was instrumented to measure the induced bending moment along the piles due to excavation of an adjacent slope. The green field lateral soil movement profiles and the lateral pile deflection profiles were monitored by in-soil and in-pile inclinometers, respectively. The unexpected early arrival of a rain storm prior to the year-end monsoon caused the failure of the slope, which resulted in the severe damage of this pile group located at the slope crest. This paper examines the prefailure and postfailure behavior of the pile group and it is demonstrated that considering the uncracked and cracked bending stiffness of the piles is vital when evaluating the progressive damage of the pile group due to slope failure.