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175 years ago today

It’s really only a couple of sentences, thanks to a whole bunch of commas and semicolons that probably should be periods.

You can find it in the appendix to volume IX of the United States Statutes at Large.

And despite the almost unanimous vote of the Congress to allow it, there were deep divisions over whether it was the right thing to do.1

Nonetheless, 175 years ago today, the United States officially went to war with Mexico:2

Mexican War

The reference in the proclamation by President Polk to the act of Congress is to Chapter 16 of the Laws of 1846, signed into law that same day — 13 May 1846 — declaring first that “by an act of the Republic of Mexico, a state of war exists between that Government and the United States,” and authorizing the President to use all existing military forces of the country, to call out the militia for not more than six months, and to enlist up to 50,000 volunteers in companies, battalions, squadrons and regiments organized by state of enlistment.3

And so it began, doing what we as genealogists are always so grateful for: creating a ton of records.

Some of these are pure military records and are readily available for free online. Check out, for example, the collection “United States Mexican War Index and Service Records, 1846-1848” on FamilySearch.

It’s not a complete index by any means, since it doesn’t include those who served in regular Army, and of course spelling of an ancestral surname can be … um … challenging in these records. But it’s a really good place to start, and the really nice thing about this is that it includes digital images of what are called the Compiled Military Service Records (CMSR) — index cards abstracting service information — for men who served from Mississippi, Pennsylvania, Tennessee, Texas, and the Mormon Battalion (Iowa).

The next collection to look at is the one entitled “United States Mexican War Pension Index, 1887-1926” — we want to see if our ancestor who served, or his widow, got a pension for that service. The best part about this index is that it includes people like (sigh) The Legal Genealogist‘s own second great grandfather who applied but were turned down.4

But, as is true for so many critical records from this time period, not everything is available online. In fact, most of the records underlying these index entries won’t be online.

Then what?

The reality is, much of this research has to be done in textual records at the National Archives. You can get some idea of the scope of what might be available from the NARA online finding aid for the Mexican War military records and the broader reference guide Military Resources: Mexican War, 1846-1848.

Some types of documents like bounty land files or pension records — even records of unsuccessful pension applications like those in my family — can be ordered from the National Archives or from private research services that do records retrieval once the archives repositories fully reopen.

So don’t get frustrated if you find an ancestor in the indexes right now and can’t put your hands on the records for a while yet.

Just be thankful that 175 years ago a paper trail began.

With a document proclaiming the war.

Cite/link to this post: Judy G. Russell, “Proclaiming the war,” The Legal Genealogist ( : posted 13 May 2021).


  1. See generally “The Senate Votes for War against Mexico,” U.S. Senate, ( : accessed 13 May 2021).
  2. Proclamation No. 2, “Respecting the War with Mexico,” 9 Stat. 999-1000 (13 May 1846).
  3. “An Act providing for the Prosecution of the existing War between the United States and the Republic of Mexico,” 9 Stat. 9-10 (13 May 1846).
  4. I love George Washington Cottrell. He’s my favorite ancestor. But he didn’t serve in the Mexican War no matter what he told the pension office… See “George Washington Cottrell of Texas: One Man or Two?,” National Genealogical Society Quarterly 105 (September 2017): 165-179.
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