It was formed in March 1915, under the command of General Sir Ian Hamilton, at the beginning of the Gallipoli campaign of the First World War.

[1] The MEF was originally commanded by General Sir Ian Hamilton until he was dismissed due to the failure of the 29th Division at Gallipoli.

Once Salonika became the sole Mediterranean theatre the MEF was commanded by General Sir Archibald Murray who was based in Egypt and whose command also involved defence of the Suez Canal from Turkish attacks.

As the importance of the Sinai front grew, a separate headquarters called the Egyptian Expeditionary Force was formed (in March 1916).

Supposedly when Secretary of State for War Lord Kitchener, was preparing the Mediterranean expedition he intended to name the headquarters the Constantinople Expeditionary Force but Hamilton suggested this might be a bit of a giveaway and also noted in his diary, "I begged him to alter this to avert Fate's evil eye.