As part of a larger experimental program on dam breaching, this paper presents experimental results for a series of breach tests conducted on homogeneous non-cohesive embankments under several initial breach conditions. The initial conditions utilized different geometries including a V-notch cut into the crest of the embankment, which is typical of a number of previous experimental studies, as well as the more realistic mechanisms of overtopping over a flat crest, and the novel breach overtopping mechanism of simulating a crater caused by an explosive blast. The relative failure rates of each of the three initial breach geometries were compared against each other, as well as against previous experimental studies. It was found that the breach initiation mechanism has a strong influence on the time required for the breach to progress to failure. Based on the experimental results, a four-stage breach process is proposed to describe breach morphology and outflow.