Following the failure of the August offensive, further operational momentum was lost. The Allied forces consolidated their positions and the Allied Command re-considered their next move. Meanwhile, Bulgaria entered WW1 on the side of the Central Powers. This forced the Allies to open a second Mediterranean front at Salonika in October 1915. Faced with competing demands, and clear failure at Gallipoli, the Allied Command replaced Sir Ian Hamilton as Field Commander and planned an evacuation.
In stark contrast to the conduct of the landings and the successive offensives, the evacuation was conducted with extraordinary skill and success. Between late December and early January, all Allied held sectors were evacuated – over 140,000 soldiers.  Despite fears of heavy casualties in the face of expected Turkish attacks, only two soldiers were wounded in the evacuations.
However, determining the total number of Allied soldiers on the Peninsula is quite difficult. Secondary sources vary widely in their descriptions of the troops involved in the campaign. One source reports over 83,000 men had to be evacuated, whilst another source states 140,000 Allied soldiers were evacuated. Yet research by this website suggests that there were at least 10 Allied divisions (plus supporting forces) engaged across the three sectors of Anzac, Cape Helles and Suvla – with a typical establishment strength of 18, 000 men per division, it would seem that greater than 180, 000 soldiers had to be evacuated. However, many divisions had suffered enormous losses from battlefield casualties and disease, which could account for the widely varying reported troop numbers.
 The figure of 140,000 soldiers to be evacuated is taken from http://web.archive.org/web/20061215101114/http://www.turkeyswar.com/campaigns/gallipoli_cont4.htm.