Infantry timelines · Infantry numbers 1–200

23d Infantry Regiment

A century of division assignments

1916–2026 · Regimental service, battle groups, battalions and deployments.

23d Infantry Regiment unit graphic
23d Infantry Regiment
First division shown2d Infantry Division22 Sep 1917
Separate battalion histories4 documented elementsDated lineages and service notes below
Page cutoff8 September 2026Last-documented status is explicitly marked

One regiment, separate assignments

The common row follows the regiment. After its reorganization, battle groups and battalions could hold different assignments at the same time. A deployment or temporary attachment does not by itself change the assigned division. The common row closes on 20 Jun 1957; later service belongs to the separate element rows. Battalion rows follow headquarters lineages, often descended from lettered companies, rather than assuming that the old regimental battalions continued unchanged.

Division patches

2d Infantry Division9th Infantry Division4th Infantry Division25th Infantry Division

Representative division patches. Patterns could change over time; an image does not imply that the exact version was worn throughout every period. Divisions without a verified asset remain identified by name.

The dated record

Division timeline

Battalion overview →

Deployments, operations and credited campaign service appear inside assignment cards. Award years establish credited service, not exact tour dates. Some service notes identify only company-sized elements. This is a sourced selection, not a complete movement log.

Assignment ends are exclusive: the next period starts on that date. *Striped final bars mean last documented, with later status unverified through the page cutoff. Unknown intervals are not treated as inactive.

  1. 1 Jan 1916 – 22 Sep 1917

    23d Infantry Regiment

    Assignment not established

    The available record does not establish a precise assignment throughout this interval. No division is inferred.

    Source

  2. 22 Sep 1917 – 20 Jun 1957

    23d Infantry Regiment

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

    Deployments & overseas operations

    1. 1918

      France: Aisne, Aisne-Marne, St. Mihiel and Meuse-Argonne

      23d Infantry Regiment · Campaign service

      Campaign participation is recorded in the Army lineage. The year label summarizes campaign service, not an exact overseas tour.

      Source

    2. 1944-1945

      Normandy, Northern France, Rhineland, Ardennes-Alsace and Central Europe

      23d Infantry Regiment · Campaign service

      Campaign participation is recorded in the Army lineage. The year label summarizes campaign service, not an exact overseas tour.

      Source

    3. 1950-1953

      Korea

      23d Infantry Regiment · Campaign service

      Campaign participation is recorded in the Army lineage. The year label summarizes campaign service, not an exact overseas tour.

      Source
  3. 20 Jun 1957 – 16 Dec 1957

    1st Battle Group / Battalion lineage

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

  4. 16 Dec 1957 – 25 Jan 1963

    1st Battle Group / Battalion lineage

    No assigned division

    The cited record establishes service outside an assigned division. Higher headquarters and temporary operational attachments could still direct the unit.

    Source

  5. 25 Jan 1963 – 16 Dec 1986

    1st Battle Group / Battalion lineage

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

  6. 16 Dec 1986 – 16 Apr 1995

    1st Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  7. 16 Apr 1995 – 27 Jul 2005

    1st Battle Group / Battalion lineage

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

    Deployments & overseas operations

    1. 2003-2004

      Iraq

      1st Battle Group / Battalion lineage · Credited overseas service

      The Army lineage lists a unit decoration for service in these years. These are credited service years, not exact deployment and return dates.

      Source
  8. 27 Jul 2005 – page cutoff*

    1st Battle Group / Battalion lineage

    Last documented: 2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage. The source establishes this last recorded status, not uninterrupted service through 2026. The striped bar extends to the page cutoff to keep the later research gap visible.

    Source

    Deployments & overseas operations

    1. 2006-2007

      Iraq

      1st Battle Group / Battalion lineage · Credited overseas service

      The Army lineage lists a unit decoration for service in these years. These are credited service years, not exact deployment and return dates.

      Source
  9. 20 Jun 1957 – 14 Jun 1958

    2d Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  10. 14 Jun 1958 – 21 Jun 1971

    2d Battle Group / Battalion lineage

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

  11. 21 Jun 1971 – 21 Jan 1983

    2d Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  12. 21 Jan 1983 – 28 Sep 1990

    2d Battle Group / Battalion lineage

    9th Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

  13. 28 Sep 1990 – 1 Jun 2006

    2d Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  14. 1 Jun 2006 – 16 Mar 2014

    2d Battle Group / Battalion lineage

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

    Deployments & overseas operations

    1. 2007-2008

      Iraq

      2d Battle Group / Battalion lineage · Credited overseas service

      The Army lineage lists a unit decoration for service in these years. These are credited service years, not exact deployment and return dates.

      Source

    2. 2009-2010

      Iraq

      2d Battle Group / Battalion lineage · Credited overseas service

      The Army lineage lists a unit decoration for service in these years. These are credited service years, not exact deployment and return dates.

      Source
  15. 16 Mar 2014 – page cutoff*

    2d Battle Group / Battalion lineage

    Last documented: 4th Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage. The source establishes this last recorded status, not uninterrupted service through 2026. The striped bar extends to the page cutoff to keep the later research gap visible.

    Source

  16. 20 Jun 1957 – 25 Jan 1963

    4th Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  17. 25 Jan 1963 – 20 May 1963

    4th Battle Group / Battalion lineage

    No assigned division

    The cited record establishes service outside an assigned division. Higher headquarters and temporary operational attachments could still direct the unit.

    Source

  18. 20 May 1963 – 14 Jan 1966

    4th Battle Group / Battalion lineage

    172d Infantry Brigade · Separate

    This headquarters is not a division. Temporary attachments in the service entries below are distinct from the formal assignment.

    Source

  19. 14 Jan 1966 – 5 Jun 1972

    4th Battle Group / Battalion lineage

    25th Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

    Deployments & overseas operations

    1. 1966-1970

      Vietnam

      4th Battle Group / Battalion lineage · Credited overseas service

      The Army lineage lists a unit decoration for service in these years. These are credited service years, not exact deployment and return dates. More than one assignment falls in the opening year; this year-level service marker does not establish the assignment on a particular deployment day.

      Source
  20. 5 Jun 1972 – 2 Aug 1972

    4th Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  21. 2 Aug 1972 – 6 Jan 1983

    4th Battle Group / Battalion lineage

    172d Infantry Brigade · Separate

    This headquarters is not a division. Temporary attachments in the service entries below are distinct from the formal assignment.

    Source

  22. 6 Jan 1983 – 21 Jan 1983

    4th Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  23. 21 Jan 1983 – 28 Sep 1990

    4th Battle Group / Battalion lineage

    9th Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

  24. 28 Sep 1990 – 16 Mar 2004

    4th Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  25. 16 Mar 2004 – 16 Dec 2006

    4th Battle Group / Battalion lineage

    172d Infantry Brigade · Separate

    This headquarters is not a division. Temporary attachments in the service entries below are distinct from the formal assignment.

    Source

  26. 16 Dec 2006 – 17 Apr 2007

    4th Battle Group / Battalion lineage

    Inactive

    The unit or its headquarters lineage was inactive. This status does not imply that every inherited honor or divisional affiliation was erased.

    Source

  27. 17 Apr 2007 – 22 Jul 2010

    4th Battle Group / Battalion lineage

    2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage.

    Source

  28. 22 Jul 2010 – page cutoff*

    4th Battle Group / Battalion lineage

    Last documented: 2d Infantry Division

    Division names are normalized across historical redesignations. This entry follows the cited unit lineage. The source establishes this last recorded status, not uninterrupted service through 2026. The striped bar extends to the page cutoff to keep the later research gap visible.

    Source

Service note · dates incomplete

5th Battalion · Alaska

The regimental history records activation on 14 January 1966 with the 172d Infantry Brigade. A complete assignment sequence is not established here.

Source

Sources and scope

Army Center of Military History lineage certificates provide the dated backbone. Regimental associations and secondary histories supplement individual operations and battalions. Where the evidence stops, the page says so. A page cutoff is not a claim that every unit directory was current on that date.

Earlier battalions are covered by common regimental service; separately dated lineages and substantiated later battalions receive their own rows or notes. A unit graphic alone is not evidence of a battalion assignment. Reserve, training and inactive organizations are distinguished from active combat units.

  1. U.S. Army Center of Military History: 23d Infantry Regiment
  2. U.S. Army Center of Military History: 1st Battalion 23d Infantry Regiment
  3. U.S. Army Center of Military History: 2d Battalion 23d Infantry Regiment
  4. U.S. Army Center of Military History: 4th Battalion 23d Infantry Regiment
  5. 23d Infantry Regiment history (Wikipedia; secondary)

Patch artwork

Unmodified artwork from Wikimedia Commons; individual file pages identify the artist and license. Insignia represent the divisions, not regimental affiliation badges.