The results here also help to resolve an existing controversy as to whether metal dendrite growth is dominated by fracture or by internal reduction of lithium ions to lithium metal. Since the experiments are conducted under conditions where dendrite growth due to internal reduction of lithium ions remains possible, yet no evidence of such growth occurs when stress-deflection is active, it is concluded that, at least for the materials tested here, metal dendrite growth proceeds by mechanical fracture rather than electronic conduction based internal Li + reduction.