Featherston Camp was the largest of the military camps in New Zealand where reinforcements for the New Zealand Expeditionary Force trained during the First World War. Most army personnel trained at Trentham Camp from October 1914 until July 1915, when the Defence Department was forced to revise its training arrangements after Trentham was hit by an outbreak of respiratory diseases, measles, and cerebro-spinal meningitis, due in part to overcrowding. Featherston Camp was developed from July 1915, and together with its satellite camps at Tauherenikau and Papawai, could accommodate 9850 men in huts and tents. Its campsites and training grounds collectively covered 1861 acres (753 ha) of land in the Featherston–Greytown area.  Around 60,000 New Zealand military personnel who subsequently served overseas spent time at Featherston Camp, about two-thirds of the total.  The Defence Department built an isolation ward complex at the southern end of the camp in early 1917.