A three-stage surge protection device protects against complex, time-variant voltage transients, including those resulting from a high-altitude nuclear electromagnetic pulse or a solar coronal mass ejection. The device relies on interaction between a snubbing low-pass filter, a transient voltage suppressor, and an electronic crowbar circuit. The low-pass filter significantly lowers the let-through voltage of the device for short-duration pulses, and helps to spread the energy to more effectively utilize the transient voltage suppressor. The transient voltage suppressor limits the let-through voltage to a clamping level and provides indication to the crowbar circuit when it is no longer able to do so. Once the clamping level is no longer able to be maintained, the crowbar circuit draws enough current to trip an upstream protective device, such as a breaker or fuse.