Active warfare throughout history has mainly been a matter for men, but women have also played a role, often a leading one. While women rulers conducting warfare was common, women who participated in active warfare was rare. The following list of women in war and their exploits from about 1800 up to about 1899 can only indicate the involvement of women, some of them thrust into positions of leadership by accident of birth or family connection, others by force of circumstance from humble origins.
Only women active in direct warfare, such as warriors, spies, and women who actively led armies are included in this list.
1808: Agustina de Aragón defends Spain during the Spanish War of Independence. Legend has it that during the bloody sieges of Saragossa, the Spanish troops abandoning their posts before falling to nearby French bayonets, she runs forward, loads a cannon, and lights the fuse, shredding a wave of attackers at point blank range. The sight of a lone woman bravely manning the cannons inspires the fleeing Spanish troops and other volunteers to return and assist her. She would later become a professional officer in the Spanish Army.
1808-1809: Elisa Bernerström enlists in the Swedish army dressed as a man because "She had decided to live and to die with her husband", the soldier Bernhard Servenus; she participates in the war between Sweden and Russia about Finland, and during one battle, she collected the ammunition of the Russians and gave them to her comrades. She is later discovered, fired but decorated with a medal for bravery in battle.
1815: William Brown (birth name unknown), a Royal Navy sailor, is discovered to be a woman. She is the first black woman to serve in the Royal Navy.
1815: Several women are found dead in British uniforms after the Battle of Waterloo, among them Mary Dixon, who dies in service after having served sixteen years in the British army dressed as a man 
1817: La Pola is executed by the Spanisn after having served as a spy during the Colombian war of Independence
1817: Gertrudis Bocanegra, a woman who raised a female army to fight in the Mexican War of Independence, is arrested, tortured, and executed.
1822: Angelique Brulon, a female soldier who had in defence of Corsica from 1792–1799, is promoted to lieutenant. She had originally fought while disguised as a man, but eventually fought openly as a woman. She retires the same year.
1831: Countess Emilia Plater creates her own group to fight in the Polish November Uprising. She becomes commanding officer of a company of infantry in the rank of captain. She dies from illness contracted during a forced march in December 1832. Several other women served openly as soldiers during this Polish rebellion against Russia, although not many are named; Soltyk reported that a beautiful girl of eighteen fought at the Russian crossfier at the Vola trenches in Warsaw the 4th September 1831, and he added that "there where not one troop of our army, where not one or more of these heroines fought."
1836: The Warner Sisters come to Constitution Island . For a half century, Susan and Anna Warner wrote popular novels and taught Sunday School to West Point cadets. Susan wrote a Wide Wide World, one of the nation's best sellers, in the 1850s. Anna wrote the words to the children's verse “Jesus Loves Me.” They later donated the island to the United States Military Academy in 1908. The remains of both sisters lie in the West Point cemetery.
1838-1839: Johanna Martens serve in the Dutch army dressed as a man to be near to her lover, a soldier 
Women were first officially assigned as keepers in the Lighthouse Service of the U.S. Coast Guard beginning in the 1830s although many wives and daughters of keepers had previously served as keepers when their husbands or fathers became ill. Women continued as lighthouse keepers until 1947.
1842: Kuilix, a female warrior of the Pend d'Oreilles leads a group of warriors to rescue another group from the Blackfeet. Women of both the Pend d'Oreilles and the related Flathead tribe actively participated in warfare, entering battles and dancing in war dances.
Mexican War (1846-1848): Elizabeth Newcom enlists in Company D of the Missouri Volunteer Infantry as Bill Newcom. She marches 600 miles from Missouri to winter camp at Pueblo, Colorado, before she is discovered to be a woman and discharged. In 1846 Sarah Borginnes is hailed as the "Heroine of Fort Brown" following her actions during the Siege of Fort Texas. She goes on to operate a series of inns providing food, lodging, liquor, and prostitutes to Zachary Taylor's troops.
1846: Kuilix participates in a fight against the Crow.
1859: From 1859 to 1862 Maria Andreu (a.k.a. Maria Mestre de los Dolores) served as the Keeper of the St. Augustine Lighthouse in Florida, becoming the first Hispanic-American woman to serve in the U.S. Coast Guard and the first Hispanic-American woman to oversee a federal shore installation.
Civil War (1861-1865): Women provide casualty care and nursing to Union and Confederate troops at field hospitals and on the Union Hospital Ship Red Rover. Biologically female soldiers on both sides wear male clothing in order to serve; some of them, such as Albert Cashier, were transgender men. By the end of the war, over 500 fully paid positions were available to women as nurses and in the United States Military.
1861: Dr. Mary Walker was a doctor with the Union Army at the First Battle of Bull Run (Manassas) and three later major engagements, but was later captured and spent the remainder of the war as a prisoner of war. She held the rank of captain. She was the first American female prisoner of war; she was captured on April 10, 1864, when she took a wrong turn while trying to get to a sick patient. The Confederates imprisoned her in the military prison in Richmond, VA, known as "Castle Thunder", and she was released on August 12, 1864, in exchange for a Confederate major. At war's end, she received the Medal of Honor for her service and for hardships endured as a POW. She is the only female to ever receive this honor. When the criteria for awarding the medal changed in 1917, Dr. Walker’s medal was rescinded along with 900 others, but in 1977, due to the persistent efforts of the Walker family, the Army Board of Corrections reviewed the case and reversed the 1917 decision, thus restoring the Medal of Honor to Dr. Walker.
1861–1865: Harriet Tubman, an abolitionist and a former slave, becomes an Union spy. She also served as a scout and nurse, and she passed undetected through Confederate lines and acted as a liaison between Union troops and recently freed black slaves. She led a band of scouts and provided key intelligence to the Union Army. Tubman became the first woman to lead an armed assault during the Civil War in the Raid at Combahee Ferry in 1863. In 1913, Tubman was buried with full military honors at Ft. Hill Cemetery, Auburn, NY.
1862: Susan King Taylor, at fourteen, becomes the first African American army nurse in the United States.
March 20, 1862: Malinda Blalock disguises herself as a man and registers as "Samuel Blalock" in the Confederate military. She fights in three battles with her husband, who was her sergeant.
1862: Four sisters of the Holy Cross and five black women served aboard the Navy's first hospital ship, RED ROVER, to provide medical care.
1863: Pauline Cushman, an actress, served on the Union side as a spy dressed in male uniform. She was given a volunteer reserve commission as a major by President Abraham Lincoln, and became known as Miss Major Cushman. By the end of the war in 1865 she was touring the country giving lectures on her exploits as a spy, and was presented by P.T. Barnum in New York.
January 25, 1865: Florena Budwin dies and becomes the first American woman to be buried in a national cemetery. She had disguised herself as a man in order to fight on the side of the Union Army in the American Civil War.
February 17, 1865: Confederate soldier Mollie Bean is captured by Union forces in the American Civil War while disguised as a man. When questioned, she said she had served for two years and that she was wounded twice.
July 25, 1865: Retired military Inspector General, H.M. Army Hospitals, Doctor James Barry, dies. Upon inspection of the corpse, it is discovered that Barry was in fact, female-bodied.
1866-1868: The only known female Buffalo Soldier was Cathay Williams, a Missouri slave. She disguised herself as a man, William Cathay, and enlisted in one of six black infantry units after the Civil War. She served from November 15, 1866, until her discharge on October 14, 1868, and her true identity was not discovered until she applied for an Army pension in 1891.
1885: Women started serving with the Canadian military in 1885, as nurses.
1883 : Marieta de Veintemilla, the niece and first lady of president Ignacio de Veintemilla, takes control of the capital, the government and its military forces in the name of her her absent uncle and commands the defense of the capital of Quito when it is attacked by the rebels.
1898: Spanish-American War (1898): Thousands of US soldiers sick with typhoid, malaria, and yellow fever overwhelm the capabilities of the Army Medical Department. Dr. Anita Newcomb McGee suggests to the Army Surgeon General that the Daughters of the American Revolution (DAR) be appointed to select professionally qualified nurses to serve under contract to the US Army. Before the war ends, 1,500 civilian contract nurses are assigned to Army hospitals in the US, Hawaii, Cuba, Puerto Rico, Guam and the Philippines, as well as to the Hospital Ship Relief. Twenty nurses die. 32 black women serve as Army contract nurses during the Spanish-American War. The 32 were thought to be immune to yellow fever during the yellow fever and typhoid epidemics, but at least three of them die from their exposure to the illness. A total of 80 African-American professional nurses serve under contract with the Army, including five graduates from the prestigious Tuskegee Institute. The Army appoints Dr. McGee Acting Assistant Surgeon General, making her the first woman ever to hold the position. The Army is impressed by the performance of its contract nurses and asks Dr. McGee to write legislation creating a permanent corps of nurses.