Editing 1915 (section)

=== May ===
{{main|May 1915}}
* [[May 1]] –  General [[Louis Botha]], [[Prime Minister of South Africa]], leads the army in the occupation of [[German South West Africa]].
* [[May 5]] – WWI: Gallipoli Campaign – Forces of the [[Ottoman Empire]] begin shelling [[ANZAC Cove]] from a new position behind their lines.
* [[May 6]] – [[Imperial Trans-Antarctic Expedition]]: [[SY Aurora's drift|SY ''Aurora'''s drift]] – The {{SY|Aurora}} breaks loose from its anchorage during a gale, beginning a 312-day ordeal.<ref>{{cite book|last=Haddelsey|first=Stephen|title=Ice Captain|publisher=The History Press|location=Stroud, Gloucestershire|year=2008|isbn=978-0-7509-4348-2|pages=51–2}}</ref>
* [[May 7]] – WWI
** [[Sinking of the RMS Lusitania|Sinking of the RMS ''Lusitania'']]: {{RMS|Titanic}}'s main rival, the British [[ocean liner]] {{RMS|Lusitania}}, is sunk by [[Imperial German Navy]] [[U-boat]] ''[[SM U-20 (Germany)|U-20]]'' off the south-west coast of Ireland, killing 1,199 civilians en route from New York City to [[Liverpool]]. The best-known of the celebrities on board is American sportsman [[Alfred Gwynne Vanderbilt]] (b. [[1877]]).
** Germany captures the Latvian port city of [[Liepāja|Libau]].
* [[May 9]] – WWI – [[Second Battle of Artois]]: [[German Empire|German]] and [[French Third Republic|French]] forces fight to a standstill; German forces defeat the British at the [[Battle of Aubers Ridge]].
* [[May 17]] – The last purely [[Liberal Party (UK)|Liberal]] government in the United Kingdom ends, when the prime minister [[H. H. Asquith]] forms an all-party [[coalition government]], the [[Asquith coalition ministry]], effective [[May 25]].
* [[May 19]] – WWI: The [[third attack on Anzac Cove]] by Ottoman forces is repelled by the [[Australian and New Zealand Army Corps]].
* [[May 22]]
** [[Quintinshill rail disaster]] in Scotland: The collision and fire kill 226, mostly troops, the largest number of fatalities in a [[List of rail accidents in the United Kingdom|rail accident in the United Kingdom]].
** [[Lassen Peak]], one of the [[Cascade Volcanoes]] in [[California]], erupts, sending an ash plume 30,000 feet in the air, and devastating the nearby area with [[pyroclastic flow]]s and [[lahar]]s. It is the only volcano to erupt in the contiguous United States this century, until the [[1980 eruption of Mount St. Helens]].
* [[May 23]] – WWI: [[Kingdom of Italy|Italy]] joins the [[Allies of World War I|Allies]] after declaring war on [[Austria-Hungary]].
* [[May 25]] – [[Republic of China (1912–49)|China]] agrees to the [[Twenty-One Demands]] of the Japanese.
* [[May 27]] – [[Armenian genocide]]: The [[Temporary Law of Deportation|Tehcir Law]] is promulgated by the Turkish [[Ottoman Empire]] authorizing deportation of the [[Ottoman Armenian population]] to [[Deir ez-Zor]] in the Syrian desert, leading to the deaths of anywhere between 800,000 and over 1,500,000 civilians and confiscation of their property.<ref>{{cite book |last1=Akçam |first1=Taner |author1-link=Taner Akçam |title=[[A Shameful Act]] |date=2006 |publisher=Henry Hold and Company |isbn=978-0-8050-8665-2 |page=249}}</ref>
* [[May 28]] – [[International Congress of Women]] meets at the Hague as a major peace initiative.<ref>{{cite book|last=Paull|first=John|year=2018|url=https://www.academia.edu/36546779|chapter=12:The Women Who Tried to Stop the Great War: The International Congress of Women at The Hague 1915|editor=Campbell, A. H.|title=Global Leadership Initiatives for Conflict Resolution and Peacebuilding|pages=249–266|location=Hershey, PA|publisher=IGI Global|doi=10.4018/978-1-5225-4993-2.CH012 |access-date=May 27, 2021|archive-date=March 25, 2022|archive-url=https://web.archive.org/web/20220325143727/https://www.academia.edu/36546779|url-status=live}}</ref> 
* [[May 29]] – [[Teófilo Braga]] becomes president of [[First Portuguese Republic|Portugal]].