This Diorama depicts one of the lesser known campaigns of World War 1, the Gallipoli Campaign. From Wikipedia:
The Gallipoli Campaign, also known as the Dardanelles Campaign, was a campaign of World War I that took place on the Gallipoli peninsula in the Ottoman Empire between 25 April 1915 and 9 January 1916. Britain and France launched a naval attack followed by an amphibious landing on the peninsula with the eventual aim of capturing the Ottoman capital of Constantinople (modern-day Istanbul). The naval attack was repelled and, after eight months' fighting, with many casualties on both sides, the land campaign also failed and the invasion force was withdrawn to Egypt.