With the rank of brigadier general, Pakenham commanded the 2nd (South Midland) Brigade of the British 2nd Mounted Division, a yeomanry unit, during World War I. The division was initially based in Egypt but was sent dismounted to Suvla on the Gallipoli peninsula as reinforcements during the Battle of Sari Bair. On August 21, 1915 the division was in reserve for the final attack on Scimitar Hill. When the initial attack by the 29th Division failed, the yeomanry were ordered to advance in the open across a dry salt lake. Raked by shrapnel fire, most of the brigades halted in the shelter of Green Hill but Pakenham led his brigade in a charge which captured the summit of the hill. As he continued to advance, he was killed.
Pakenham's body was never recovered as the British made no further advances before the evacuation of Suvla on December 20. His grave is marked as a special memorial in Green Hill Cemetery at Suvla.
| Preceded by: William Pakenham | Earl of Longford | Followed by: Edward Pakenham |