Cardigan formed up his unit and charged the length of the Valley of the Balaclava, under fire from Russian batteries in the hills. The charge of the Light Brigade caused 278 casualties of the 700-man unit. The Light Brigade was memorialized in the famous poem by Alfred Lord Tennyson, "The Charge of the Light Brigade." Although traditionally the charge of the Light Brigade was looked upon as a glorious but wasted sacrifice of good men and horses, recent historians say that the charge of the Light Brigade did succeed in at least some of its objectives. The aim of any cavalry charge is to scatter the enemy lines and frighten the enemy off the battlefield. The charge of the Light Brigade had so unnerved the Russian cavalry, which had previously been routed by the Heavy Brigade, that the Russian Cavalry was set to full-scale flight by the subsequent charge of the Light Brigade.:252
Who wrote the famous poem about the Light Brigade?  (If the question is unanswerable, say "unanswerable")
Alfred Lord Tennyson