Studies on crack propagation in a model glass‐matrix composite were undertaken to observe how the crack propagates around a nonfailing elastic reinforcing fiber. The model system consisted of a 1.6‐mm‐diameter ferrous alloy rod embedded in a glass that very closely matched the thermal expansion of the alloy. Cracks were driven through the glass so as to intersect the rod. The crack trajectory, spallation region, and debonding effects are described. A computational model is offered for the spallation needed to accommodate crack opening in the absence of significant matrix compl