THE 90th anniversary of the Battle of the Somme will be marked at the National Trust?s Castle Drogo this weekend. The Drewe family, who built Castle Drogo, were particularly affected by the first world war as Adrian, the eldest son, was killed at Ypres in 1917. The 90th anniversary of the battle, on Saturday July 1, will feature a War Poets Weekend. Visitors will be able to follow a war poetry trail around the castle and learn more about the momentous events that were taking place at the time the poems were written. In addition, they can explore the history of the castle covering the same period. The trail will finish in the memorial room dedicated to Adrian Drewe. The event will be held on Saturday July 1 and Sunday July 2, from 11am to 5pm. Normal admission charges will apply. The Battle of the Somme on July 1 1916 saw the biggest ever casualties ? more than 57,000 ? for the British Army in a single engagement.