Why early night actions closed to spar range

The Moonlight Battle of St Vincent shows that a night action could be fought at literal spar range. Before useful low-light sensors, ships could engage only as far away as their crews could see. Early twentieth-century weapons made such proximity even more dangerous, because aim became almost point-blank and armour offered little reassurance. Collision and catastrophic short-range damage therefore remained central problems as navies entered the dreadnought era.