Infantry timelines · Infantry numbers 1–200

18th Infantry Regiment

A century of division assignments

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

18th Infantry Regiment unit graphic
18th Infantry Regiment
First division shown1st Infantry Division8 Jun 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 15 Feb 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

1st Infantry Division8th Infantry Division24th 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 – 8 Jun 1917

    18th Infantry Regiment

    Assignment not established

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

    Source

  2. 8 Jun 1917 – 15 Feb 1957

    18th Infantry Regiment

    1st Infantry Division

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

    Source

    Deployments & overseas operations

    1. 1918

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

      18th 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. 1942-1945

      North Africa, Sicily, Normandy and Central Europe

      18th 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. 15 Feb 1957 – 14 Apr 1959

    1st Battle Group / Battalion lineage

    1st Infantry Division

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

    Source

  4. 14 Apr 1959 – 1 Apr 1963

    1st Battle Group / Battalion lineage

    8th Infantry Division

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

    Source

  5. 1 Apr 1963 – 1 Nov 1983

    1st Battle Group / Battalion lineage

    1st Infantry Division

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

    Source

    Deployments & overseas operations

    1. 1965-1970

      Vietnam

      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
  6. 1 Nov 1983 – 16 Jun 1989

    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 Jun 1989 – 16 Aug 1991

    1st Battle Group / Battalion lineage

    197th Infantry Brigade · Separate

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

    Source

  8. 16 Aug 1991 – 16 Feb 1996

    1st Battle Group / Battalion lineage

    24th Infantry Division

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

    Source

  9. 16 Feb 1996 – 16 Mar 2008

    1st Battle Group / Battalion lineage

    1st Infantry Division

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

    Source

    Deployments & overseas operations

    1. 2004-2005

      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

    2. 2006-2007

      Baghdad, 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
  10. 16 Mar 2008 – page cutoff*

    1st Battle Group / Battalion lineage

    Last documented: 1st 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. 2008-2009

      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. 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

    2. 2010-2011

      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

    3. 2015-2016

      Central and Southwest Asia

      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
  11. 15 Feb 1957 – 1 Oct 1963

    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. 1 Oct 1963 – 15 Apr 1970

    2d Battle Group / Battalion lineage

    1st Infantry Division

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

    Source

    Deployments & overseas operations

    1. 1965-1970

      Vietnam

      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. The labeled service overlaps an assignment change and is listed only once; consult the following assignment cards as well.

      Source
  13. 15 Apr 1970 – 16 Oct 1987

    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. 16 Oct 1987 – 16 Aug 1991

    2d Battle Group / Battalion lineage

    197th Infantry Brigade · Separate

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

    Source

    Deployments & overseas operations

    1. 1990-1991

      Saudi Arabia and Iraq

      2d Battle Group / Battalion lineage · Deployment / overseas operation

      Served in the Gulf War with the 197th Infantry Brigade, attached to the 24th Infantry Division. The labeled service overlaps an assignment change and is listed only once; consult the following assignment cards as well.

      Source
  15. 16 Aug 1991 – 15 Feb 1996

    2d Battle Group / Battalion lineage

    24th Infantry Division

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

    Source

  16. 15 Feb 1996 – 16 Oct 2009

    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

  17. 16 Oct 2009 – 1 Oct 2012

    2d Battle Group / Battalion lineage

    170th Infantry Brigade · Separate

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

    Source

  18. 1 Oct 2012 – 1 Nov 2012

    2d Battle Group / Battalion lineage

    Assignment not established

    The parent brigade inactivated during this month. A precise effective date for this battalion is not established here.

    Source

  19. 1 Nov 2012 – page cutoff*

    2d Battle Group / Battalion lineage

    Last documented: Inactive

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

4th Battalion · Berlin and 3d Armored Division

Activated with the Berlin Brigade on 1 September 1963. A later activation on 16 June 1989 assigned it to the 3d Armored Division; the association records inactivation in 1991.

Source

Service note · dates incomplete

5th Battalion · 3d Armored Division

Activated and assigned to the 3d Armored Division in Germany on 16 June 1989. The cited lineage does not establish its subsequent end date.

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: 18th Infantry Regiment
  2. U.S. Army Center of Military History: 1st Battalion 18th Infantry Regiment
  3. U.S. Army Center of Military History: 2d Battalion 18th Infantry Regiment
  4. 3d Armored Division Association: 4th Battalion, 18th Infantry lineage
  5. 3d Armored Division Association: 5th Battalion, 18th Infantry lineage
  6. U.S. Army: 170th Brigade inactivated in October 2012
  7. 18th 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.