Solution: History Meta
Answer: A CLERICAL ERA

Written by Amos Eshel and Jason Deakins

Each of the answers in this department reads like a newspaper headline and references a particular historic event...twice! These dates can be used to identify particular letters in the given calendar which looks like a month, but is extended further to be capable of handling a month that starts on any day of the week and goes as long as 31 days.

As an example, May 2023 begins on a Monday; May 7, 2023 therefore is the Sunday in the 2nd row, an A. Extracting two letters per answer and ordering them by when they occurred (which ends up just being by year, since no two events happened in the same year), yields the answer A CLERICAL ERA.

DateAnswerLetterNotes
12/10/1817MISSISSIPPI ADMITTED TO UNIONAMississippi originally becomes a state.
4/18/1853SEATTLE COUNTY NAMESAKE DIESCKing County was originally named for William R. King (the 13th VP of the USA)...
4/15/1865JOHNSON ASSUMES PRESIDENCYLAndrew Johnson, following the assassination of Abraham Lincoln.
1/11/1870 or 2/23/1870MISSISSIPPI ADMITTED TO UNIONEMississippi returns to the Union following the Civil War. Two possible dates depending on definition of readmission, both yield same letter.
2/20/1962JOHN GLENN FLIES OUT TO SPACERAs part of the Mercury 7.
11/22/1963JOHNSON ASSUMES PRESIDENCYILyndon B. Johnson, following the assassination of John F. Kennedy.
4/4/1968SEATTLE COUNTY NAMESAKE DIESC...before 1986 when it was changed to instead honor Martin Luther King, Jr.
1/17/1971COLTS WIN THE SUPER BOWLAAs the Baltimore Colts, winning Super Bowl V.
6/8/1974 or 12/28/1974BAKER STARTS PLAYING DOCTORLTom Baker first appears onscreen as the 4th Doctor (Doctor Who), or his first full episode. Both dates yield the same letter.
3/16/1984 or 3/22/1984BAKER STARTS PLAYING DOCTOREColin Baker first appears onscreen as the 6th Doctor (Doctor Who), or his first full episode. Both dates yield the same letter.
10/29/1998JOHN GLENN FLIES OUT TO SPACERAs part of a study on age related to space travel.
2/4/2007COLTS WIN THE SUPER BOWLAAs the Indianapolis Colts, winning Super Bowl LVII.
SMTWTFS
MHOWCGS
AODATTL
OSEIIEL
ACREEIL
UMDBRNY
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Author’s Notes

Amos: This meta was written before the 2022 NFL season even began, so if the Colts won Super Bowl LVII we would have had to scramble to fix things. In a previous Microsoft Puzzle hunt, I wrote a puzzle that relied on the number of championships various pro teams have won, so for this meta, Jonah suggested I should use an answer like AMOS WRITES A PUZZLE THAT BREAKS IF THE WRONG TEAM WINS THE SUPER BOWL.