Editing 1845 (section)

=== October–December ===
* [[October 9]] – The eminent and controversial [[Anglicanism|Anglican]], [[John Henry Newman]], is received into the [[Roman Catholic Church]].
* [[October 10]] – In [[Annapolis, Maryland]], the Naval School (later renamed the [[United States Naval Academy]]) opens with 50 midshipmen and seven professors.
* [[October 13]] – A majority of voters in the [[Republic of Texas]] approve a proposed constitution that, if accepted by the [[United States Congress]], will make [[Texas]] a [[U.S. state]].
* [[October 19]] – [[Richard Wagner]]'s opera ''[[Tannhäuser (opera)|Tannhäuser]]'' debuts at the [[Dresden]] Royal Court Theater.
* [[October 21]] – The ''[[New York Herald]]'' becomes the first newspaper to mention the game of baseball.
* [[November 20]] – [[Anglo-French blockade of the Río de la Plata]] – [[Battle of Vuelta de Obligado]]: The [[Argentine Confederation]] is narrowly defeated by an Anglo–French fleet on the waters of the [[Paraná River]], but the victors suffer serious damage to their ships, and Argentina attracts political support in South America.
* [[December 2]] – [[Manifest destiny]]: U.S. President [[James K. Polk]] announces to Congress that the [[Monroe Doctrine]] should be strictly enforced, and that the United States should aggressively expand into the West.
* [[December 11]] – [[First Anglo-Sikh War]]: Sikh army crosses the [[Sutlej]] in the [[Punjab (region)|Punjab]].
* [[December 22]]–[[December 23|23]] – [[Battle of Ferozeshah]] (Anglo-Sikh War): [[East India Company]] forces are victorious over those of the Sikh Empire.
* [[December 27]]
** [[Anesthesia]] is used for childbirth for the first time, by Dr. [[Crawford Long]] in [[Jefferson, Georgia]].
** American newspaper editor [[John L. O'Sullivan]] claims (in connection with the annexation of the [[Oregon Country]]) in ''[[The United States Magazine and Democratic Review]]'' that the United States should be allowed "the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions". It is the second time he uses the term ''[[manifest destiny]]'' (first in connection with the [[Republic of Texas]] in July – August), and it will have a huge influence on [[American imperialism]] in the following century.
* [[December 29]] – [[Texas]] is admitted as the 28th [[U.S. state]].
* [[December 30]] – [[Queen's University of Ireland|Queen's Colleges]] of [[Queen's University Belfast|Belfast]], [[University College Cork|Cork]], and [[National University of Ireland, Galway|Galway]] are incorporated in Ireland.