The 25th Infantry Division was formed on 1 October 1941 at Schofield Barracks, Hawaii. Its lineage can be traced to the Hawaiian Division, which defended Hawaii from 1921 to 1941. The division received its baptism of fire when Japanese forces attacked Oahu on 7 December 1941. In November 1942, the 25th Infantry Division was ordered into action against the Japanese in the Solomon Islands. Due to their superior performance during operations in the Solomons, the division earned the nickname "Tropic Lightning". The division also took part in the liberation of the Philippine Islands, landing on the island of Luzon in January 1945 and fought for 165 days without rest. After World War II, Tropic Lightning performed occupation duty in Japan. In the summer of 1950, the 25th Infantry Division was called to action in South Korea against communist aggression. Tropic Lightning deployed from Japan and immediately began operations to defend the city of Pusan. After weeks of bitter fighting, the division broke out of the "Pusan Perimeter" in September 1950 with U.S. and United Nations forces. Most of Korea was liberated when Chinese forces joined the fighting in November 1950, forcing allied forces south once again. Tropic Lightning began retaking lost territory in January 1951, fighting bitter battles until 27 July 1953, when an armistice took effect. The 25th Infantry Division returned home to Hawaii in October 1954 after a twelve year absence, with the freedom of South Korea preserved.In December 1965, Tropic Lightning answered another call to fight against communism and deployed to fight in the Vietnam War. In a massive airlift, the 3rd "Bronco" Brigade deployed to the central highlands at Pleiku; while the Division headquarters, along with the 1st "Lancer" and 2nd "Warrior" Brigades, were transported by sea. By April 1966, all division units were in country with the headquarters established in Cu Chi district, 20 miles northwest of Saigon. The Vietnam War was unlike previous conflicts; the enemy fought from the shadows and hid among the population. During its five years in South Vietnam, the 25th Infantry Division engaged in operations to destroy their elusive enemy, to include fighting during the Tet Offensive of 1968, and offensives against enemy sanctuaries in Cambodia during 1970. By April 1971, all Division units had returned to Hawaii after a seven year fight in Southeast Asia.The organization of the 25th Infantry Division changed in 1985 when it was selected to reorganize into a light infantry formation. In 1995, the Division headquarters, along with the 2nd and 3rd Brigades, were sent to Haiti as part of Operation UPHOLD DEMOCRACY. The 25th Infantry Division continued peacekeeping missions into the 21st century as 1,000 Tropic Lightning Soldiers deployed to BosniaHerzegovina from April to September 2002 as part of Stabilization Force XI. Division Soldiers took part in mine clearing operations, reconstruction, and the destruction of weapons turned in by civilians to help Bosnia-Herzegovina rebuild after a devastating civil war.At the dawn of the 21st century, the 25th Infantry Division was thrust into its fourth war. In 2004, Tropic Lightning deployed in support of the Global War on Terrorism. Like the insurgents the Division fought in the Vietnam War, the enemy avoided open battle and blended into the population. When the 2nd Brigade Combat Team deployed to northern Iraq in January 2004, where it engaged insurgent forces and helped rebuild local security and government institutions. In September of that same year, the 1st Brigade, newly transformed into a Stryker Brigade Combat Team, departed Fort Lewis, Washington, for Iraq's Ninewa Province. The culmination of their deployments occurred in January 2005, when both BCTs supported free elections for all Iraqis. The 2nd BCT returned home in March 2005, followed by the 1st BCT in September.
In March 2004, the Division headquarters along with the 3rd Brigade Combat Team, Division Artillery, 25th Aviation Brigade, and Division Support Command deployed to Afghanistan. Soldiers of Tropic Lightning engaged in combat operations against Al-Qaeda and Taliban forces, while also helping to rebuild a country ravaged by decades of war. In October 2004, free elections were held in Afghanistan, supported by Tropic Lightning Soldiers. By June 2005, all division units had returned to Schofield Barracks. These first deployments marked the beginning of almost a decade of recurring missions by Tropic Lightning units to Iraq and Afghanistan. In 2005, the 25th Infantry Division changed its organization as part of the Army's program to transform into a more versatile, agile force. As part of transformation, a Special Troops Battalion was reactivated. The Brigades also changed, with the 2nd and 3rd BCTs becoming Stryker and Infantry Brigade Combat Teams respectively, and, concurrently, the Aviation Brigade reorganized as Combat Aviation Brigade. With transformed brigades, Tropic Lightning dropped its "light" designation on 1 January 2006. The 4th Brigade, 25th Infantry Division was reactivated in July 2005 as an Airborne Brigade Combat Team. Like the 1st BCT, the 4th "Spartan" BCT was not under Division control, but carried the patch and pedigree of a Tropic Lightning unit. Eventually both the 1st and 4th BCTs would come to call Alaska home.After completing transformation, the Division Headquarters, Special Troops Battalion, Combat Aviation Brigade, and 3rd BCT deployed to northern Iraq in 2006 as part of Operation IRAQI FREEDOM 06-08. Joined by elements from four other U.S. Army divisions, Task Force LIGHTNING took control of Multinational Division-North. Just a few months later, the 4th BCT deployed to central Iraq in October 2006. During the course of the deployment, both Task Force LIGHTNING and 4th BCT focused on training Iraqi Security Forces, improving the effectiveness of local governments, and engaging in combat operations against insurgent groups. The climax of their deployments occurred during the summer of 2007, when Task Force LIGHTNING and the 4th BCT dealt the enemy a severe blow in a series of offensives as part of the "The Surge". The actions by Tropic Lightning units during this critical period decreased violence and gave local authorities the ability to reestablish effective governance, which set Iraq on the road to stability. By October 2007, all Hawaii-based Task Force LIGHTNING units returned to Schofield Barracks, and the 4th BCT returned to Alaska by December. As Division units were returning home in late 2007, the 2nd BCT was preparing for its own deployment to Iraq. From January 2008 through March 2009, the "Warrior" BCT was deployed to Iraq, conducting operations just north of Baghdad to capitalize on gains made during the Surge. While continuing to pursue insurgents and militias, the 2nd BCT also helped Iraqi officials improve governance and security forces. Just over a year later, the Division Headquarters, Special Troops Battalion, and 3rd BCT returned to northern Iraq in November 2008. Included among the U.S. Army units that comprised Task Force LIGHTNING during Operation IRAQI FREEDOM 09-11 was the Alaska-based 1st BCT. This time, the focus was on partnership to support Iraqi institutions as they assumed greater responsibility for their country. Task Force LIGHTNING also acted as an honest mediator in local disputes to help foster unity between all Iraqis, helping forge an agreement between the Iraqi central government and Kurdistan Regional Government to conduct joint operations against insurgents. In November 2009, Task Force LIGHTNING transitioned control to the 3rd Infantry Division headquarters whose forces included the 25th Infantry Division's own Combat Aviation Brigade. During its deployment, the "Wings of Lightning" CAB provided air transportation and attack support to Task Force MARNE. As a sign of things to come, CAB Soldiers began closing facilities at their base as part of the U.S./Iraqi Security Agreement before returning home in July 2010. While most Tropic Lightning units returned to Iraq, the 4th BCT deployed to Afghanistan in February 2009. Taking charge of Paktika and Paktiya Provinces, the BCT engaged enemy forces and helped build government institutions in some of the most rugged terrain in the world. These lands were no stranger to Tropic Lightning; much of the same area was patrolled by the 3rd BCT were when 25th Infantry Division units were in Afghanistan five years before. By February 2010, the 4th BCT returned to Alaska. Just weeks after returning to Hawaii, a new change had come to the 25th Infantry Division. The Division headquarters was reorganized as Headquarters and Headquarters Battalion, 25th Infantry Division on 16 January 2010, replacing the Special Troops Battalion that was deactivated the same day. In December 2010, HHBN 25ID departed on its third deployment to Iraq, following the 2nd BCT, who deployed to northern Iraq in June. The division headquarters was given the task of overseeing U.S. forces in Baghdad and Anbar Provinces as Headquarters, United States Division-Center during Operation NEW DAWN. Both the Division headquarters and the "Warrior" BCT partnered with Iraqi Security Forces to increase their capabilities and conduct joint operations against insurgents, while simultaneously transferring facilities to Iraqi government control. These missions had to be completed by the end of 2011 in accordance with the 2008 Security Agreement. For the Division headquarters, these missions had to be executed with less than half the number of Soldiers it controlled in past deployments. In the summer of 2011, the 2nd BCT redeployed back to Schofield Barracks. Meanwhile, the Division headquarters was given an additional mission: safeguard American troops as they departed Iraq, and be the last division headquarters to leave. By the time Tropic Lightning completed its mission on 18 December 2011, thousands of troops retrograded out of Iraq under its aegis, and dozens of bases were transferred to the government of Iraq. Through its outstanding performance, the 25th Infantry Division completed its final mission in Iraq with honor.While the headquarters was in Iraq, the 1st and 3rd BCTs deployed to Afghanistan in the spring of 2011, followed by the 4th BCT and CAB in November 2011. While in Afghanistan, these units fought hard to preserve freedom and democracy against insurgent forces, which were bent on keeping misery and subjugation alive. Missions included fighting and defeating enemy forces, as well as preparing local security and governance institutions for the day when they will stand on their own. By early 2013, all Tropic Lightning units had returned to their home stations.
The 25th Infantry Division has resumed its traditional role as guardian of the Pacific in recent years. Military exchanges with partner states including Japan, Taiwan, the Philippines, Thailand, Malaysia, Singapore, Indonesia, Australia, and New Zealand builds both capabilities and trust with our regional neighbors. Tropic Lightning Soldiers serve as the premier Army response force for the U.S. Pacific Command, and regularly train with other U.S. military branches to practice and maintain joint operations capabilities. The climate and terrain of the Pacific region demands Tropic Lightning Soldiers be able to operate in physically demanding and harsh environments. In 2014, the division opened the Jungle Operations Training Center--the first such school in the Army since the closing of the old Jungle Warfare School at Fort Sherman, Panama Canal Zone. Joint operations and training with partner states herald a new chapter in the history of Tropic Lightning--America's Pacific Division.