The United States military has a rich heritage dating back to the colonial era, with several regiments claiming centuries of continuous service. Among these storied units, four stand out as the oldest military regiments in American history, each with unique contributions to the nation’s defense and cultural fabric that are still active till date . 

So, in this article we’ll explore these historic regiments, their origins in early America, and their evolution into modern military units.

4. 3rd Infantry Regiment (“The Old Guard”)

In its early years, 3rd Infantry Regiment participated in numerous frontier battles, helping to secure America’s western expansion. During the War of 1812, the unit defended American sovereignty against British forces, participating in engagements that helped establish the United States as a legitimate national power.

During the Mexican-American War (1846-1848), the regiment distinguished itself in key engagements, including the Battle of Cerro Gordo, where American forces overcame challenging terrain and numerically superior Mexican positions to secure victory.

Throughout the Civil War, the regiment maintained its regular army status, serving in various capacities across multiple theaters of the conflict. Its professional training and discipline provided a model for volunteer units during this tumultuous period.

The regiment participated actively in both World Wars, engaging in combat operations that spanned European battlefields. These global conflicts transformed American military capabilities and international responsibilities, with the 3rd Infantry adapting to modern warfare’s evolving demands.

Since 1948, the regiment has served in the Modern Era as the official ceremonial unit and escort to the President, earning its nickname “The Old Guard.” This special designation reflects both its historical significance and its contemporary ceremonial importance.

The regiment’s Commander-in-Chief’s Guard traces its lineage directly to George Washington’s personal guard unit, creating a direct connection to America’s founding father and first military commander. Today, The Old Guard performs some of the nation’s most visible ceremonial duties, including the solemn responsibility of guarding the Tomb of the Unknown Soldier and conducting military funerals at Arlington National Cemetery. These ceremonial functions represent the intersection of military tradition, national identity, and respect for those who have served.

For more on historic military sites, take a look at our feature on some of the longest-standing army installations in the U.S.

3. 182nd Infantry Regiment

Formed in 1636 as part of Massachusetts’s comprehensive militia system, the 182nd Infantry Regiment developed from the 1st Middlesex Regiment, with companies drawn from communities including Concord and Sudbury. This decentralized structure reflected early American military organization, with local communities providing their own defense forces.

During the American Revolution, elements of what would become the 182nd served in various regiments of the Massachusetts Line, participating in crucial engagements that secured American independence. This period transformed colonial militia units into more formalized military organizations aligned with the Continental Army.

The regiment contributed significantly to Civil War Union efforts, participating in multiple engagements across different theaters. Its soldiers faced the harsh realities of America’s bloodiest conflict, fighting in campaigns from the Eastern seaboard to deeper Southern territories.

In both World Wars, the regiment earned commendations for battlefield performance. World War I saw the unit deploy to France as part of the American Expeditionary Force, while World War II took the regiment to the Pacific Theater, where it participated in island-hopping campaigns against Japanese forces.

The regiment’s organizational structure has evolved significantly over its history, including a notable conversion to a cavalry unit in 2006 before reverting to its traditional infantry role in 2010. This adaptability demonstrates the regiment’s ability to transform according to military needs while maintaining its historic lineage.

The regiment’s Modern Era service includes peacekeeping missions in Kosovo following the Balkan conflicts and combat deployments to Afghanistan as part of Operation Enduring Freedom, demonstrating its continued relevance in contemporary military operations.

2. 181st Infantry Regiment

Established on December 13, 1636, the 181st Infantry Regiment originated as the North Regiment before becoming known as the Middlesex Regiment. This unit shares its founding date with the 101st Field Artillery but developed a distinct infantry-focused identity.

During the American Revolution, the regiment made history by participating in the Battle of Lexington and Concord, widely regarded as the opening engagement of the Revolutionary War. Its soldiers stood at North Bridge in Concord, where the “shot heard ’round the world” was fired. The regiment later participated in the Siege of Boston and numerous other significant Revolutionary battles, cementing its place in America’s founding narrative.

The regiment’s extensive lineage includes participation in the ambitious but ultimately unsuccessful Battle of Quebec in 1775, representing American revolutionary forces’ attempt to bring Canada into the rebellion against British rule. During the Rhode Island campaign of 1780, the regiment demonstrated tactical flexibility in combined operations with French allies, foreshadowing future international military cooperation.

Throughout the Civil War, the regiment served in various campaigns under different designations, contributing significantly to Union efforts. Its soldiers fought in key battles across multiple theaters, embodying the complex and often divisive nature of this internal conflict.

The regiment’s service continued through both World Wars, earning battle honors and distinctions across European battlefields. During World War I, the unit joined the American Expeditionary Forces in France, participating in major offensives that helped secure Allied victory. In World War II, the regiment deployed to the Pacific Theater, facing Japanese forces in brutal island campaigns.

In the Modern Era, the 181st Infantry has adapted to contemporary military requirements, engaging in peacekeeping missions in the Balkans and deployments throughout the Middle East as part of the Global War on Terror. These modern missions reflect the regiment’s evolution from colonial militia to sophisticated modern infantry force.

1. 101st Field Artillery Regiment (“Boston Light Artillery”)

The 101st Field Artillery Regiment holds the distinction of being one of America’s oldest military units, tracing its lineage directly to the Massachusetts colonial militia. Initially formed to protect early settlers from various threats, the regiment has transformed over centuries while maintaining its essential identity.

During the Colonial Era, the unit served as a crucial defensive force for the Massachusetts Bay Colony, protecting settlements from Native American conflicts and potential foreign threats. Colonial militias represented the primary defensive capability of early American settlements, and the Boston Light Artillery was central to this system.

When the Revolutionary War erupted, the regiment played a pivotal role in America’s fight for independence. Its participation in the Siege of Boston (1775-1776) helped secure an early American victory that forced British forces to evacuate the city. The regiment’s artillery expertise proved invaluable during this formative conflict.

The regiment’s involvement in pivotal moments of American history extends beyond major wars. In August 1765, the unit was activated to patrol Boston during riots protesting the controversial Stamp Act, an early manifestation of colonial resistance to British taxation. Following the Boston Massacre in March 1770, elements of the regiment maintained order in the city, navigating the complex tensions between colonial citizens and British authorities.

During Shays’ Rebellion of 1786, the regiment protected judges and the Taunton courthouse from insurgents, demonstrating its role in maintaining domestic order during the fragile early years of the American republic.

During the Civil War, the regiment took on unique responsibilities, including enforcing draft laws during the tumultuous New York City Draft Riots of 1863. These riots, sparked by socioeconomic tensions and opposition to conscription policies, represented one of the most significant civil disturbances in American history. Perhaps most dramatically, in July 1863, the regiment defended the Cooper Street Armory against more than 1,000 rioters during the Boston Draft Riots, illustrating its domestic security role during this turbulent period.

The regiment’s legacy continued through both World Wars, where it provided crucial artillery support across European theaters. During World War I, the unit served in France, supporting Allied offensives with heavy artillery. In World War II, the regiment participated in multiple campaigns across the European theater, demonstrating the versatility and importance of artillery in modern warfare.

In the Modern Era, the 101st Field Artillery has maintained its relevance through adaptability and continued service. Recent deployments to Iraq and Afghanistan showcase the regiment’s ongoing contributions to American military operations, now utilizing sophisticated artillery systems and modernized training methods while maintaining connections to its historic roots.

Conclusion

These four regiments represent America’s oldest continuous military traditions. From colonial militias to modern military units, they have adapted to changing threats, technologies, and missions while maintaining connections to their historic origins. Their evolution mirrors America’s own growth from colonial outpost to global superpower, demonstrating how military traditions can both preserve history and remain relevant in contemporary contexts.