An experimental investigation of the compressive failure in masonry made of soft clay bricks is presented. The research attempts to address the concern of strong/stiff mortars available in the market today in combination with poor quality burnt clay bricks used in India. Masonry assemblages are tested to evaluate the influence of the relative strength of mortar on the observed damage evolution and compressive failure. Damage evolution associated with the formation and propagation of vertical splitting cracks during the compressive load response of masonry assemblages in the stack bonded arrangement are studied using a full-field optical technique based on digital image correlation. The stress state in the composite material produces tension in the mortar and confined compression in brick. Using image correlation clear evidence of the crack forming in the mortar and propagating into the brick is established. Failure is produced by vertical splitting and the number of cracks depends upon the tensile strength of the mortar relative to the brick and the number of head joints. Head joints act as stress risers, leading to high tensile stress. © 2017 Trans Tech Publications.