1778

January–March

• January 18 - Third voyage of James Cook: Captain James Cook, with ships HMS Resolution and HMS Discovery, first views Oʻahu then Kauaʻi in the Hawaiian Islands of the Pacific Ocean, which he names the Sandwich Islands.
• February 5 - In the United States:
• *South Carolina becomes the first state to ratify the Articles of Confederation.
• *General John Cadwalader shoots and seriously wounds Major General Thomas Conway in a duel after a dispute between the two officers over Conway's continued criticism of General George Washington's leadership of the Continental Army.
• February 6 - American Revolutionary War: In Paris, the Treaty of Alliance and the Treaty of Amity and Commerce are signed by the United States and France, signaling official French recognition of the new republic.
• February 23 - American Revolutionary War: Friedrich Wilhelm von Steuben arrives at Valley Forge, Pennsylvania and begins to train the American troops.
• March 6-October 24 - Captain Cook explores and maps the Pacific Northwest coast of North America, from Cape Foulweather to the Bering Strait.
• March 10 - American Revolutionary War: George Washington approves the dishonorable discharge of Lieutenant Frederick Gotthold Enslin, for "attempting to commit sodomy, with John Monhort a soldier".

  April–June

• April 7 - Former British prime minister William Pitt delivers his last speech to Parliament, and speaks to the House of Lords "passionately but incoherently against the granting of independence" to the American colonies, but collapses during the debate, and dies five weeks later.
• April 12 - King George III appoints the five-member Carlisle Peace Commission to present peace terms to negotiate an end to the rebellion of Britain's 13 American colonies.
• April 30 - The long Hudson River Chain, designed to prevent British ships from moving up the river toward West Point, New York is stretched across the river and anchored by an engineering team under the direction of Captain Thomas Machin.
• May 12 - Heinrich XI, Prince Reuss of Greiz is elevated to Prince of the Principality of Reuss-Greiz by Joseph II, Holy Roman Emperor. This year sees the first appearance of the modern-day national colors of Germany on a flag that closely resembles the modern flag of Germany, to occur anywhere within modern-day Germany.
• May 30 - Benedict Arnold signs the U.S. Oath of Allegiance at Valley Forge.
• June 24 - A total solar eclipse takes place across parts of North America, from Texas to Virginia.
• June 28 - American Revolutionary War: Battle of Monmouth - George Washington's Continental Army battles British general Sir Henry Clinton's army to a draw, near Monmouth County, New Jersey.
• June - The Anglo-French War begins.

  July–September

• July 3 - American Revolutionary War: The Battle of Wyoming takes place near Wilkes-Barre, Pennsylvania, ending in a terrible defeat for the local colonists.
• July 4 - American Revolutionary War: George Rogers Clark takes Kaskaskia.
• July 10 - Louis XVI of France declares war on the Kingdom of Great Britain.
• July 26 - In the Russian Empire, the forced emigration of Christians from the Crimea to Pryazovia begins.
• July 27 - American Revolutionary War: First Battle of Ushant - British and French fleets fight to a standoff.
• August 3 - The La Scala Opera House opens in Milan, with the première of Antonio Salieri's Europa riconosciuta.
• August 26 - Triglav, at above sea level the highest peak of Slovenia, is ascended for the first time by four men: Luka Korošec, Matevž Kos, Štefan Rožič, and Lovrenc Willomitzer, on Sigmund Zois' initiative.
• August 29 - American Revolutionary War: The tactically inconclusive Battle of Rhode Island takes place, after which the Continental Army abandons its position on Aquidneck Island.
• September - The Massachusetts Banishment Act, providing punishment for Loyalists, is passed.
• September 7 - American Revolutionary War: Invasion of Dominica - The French capture the British fort there, before the latter is aware that France has entered the war in the Franco-American alliance.
• September 17 - The Treaty of Fort Pitt is signed, the first formal treaty between the United States and a Native American tribe.
• September 19 - The Continental Congress passes the first budget of the United States.

  October–December

• October 12 - The Continental Congress advises the 13 member states to suppress "theatrical entertainments, horse-racing, gaming, and such other diversions as are productive of idleness, dissipation, and general depravity of principles and manners."

• November 11 - American Revolutionary War: Cherry Valley massacre - British forces and their Iroquois allies attack a fort and the village of Cherry Valley, New York, killing 14 soldiers and 30 civilians.
• November 26
• *In the Hawaiian Islands, Captain James Cook becomes the first European to land on Maui.
• *New Jersey becomes the second state to agree to the Articles of Confederation.
• December 10 - John Jay of New York is chosen as the sixth President of the Continental Congress.
• December 29 - American Revolutionary War: Capture of Savannah - British forces under Archibald Campbell take the city of Savannah, Georgia.

  Undated

• The first settlement is made in the area of modern-day Louisville, Kentucky, by 13 families under Colonel George Rogers Clark.
• Phillips Academy is founded in Massachusetts by Samuel Phillips Jr.
• The term thoroughbred is first used in the United States, in an advertisement in a Kentucky gazette, to describe a New Jersey stallion called Pilgarlick.
• Thomas Kitchin's The Present State of the West-Indies: Containing an Accurate Description of What Parts Are Possessed by the Several Powers in Europe is published in London.
• The city of Ulaanbaatar is settled at its present location, having functioned as a mobile monastic settlement since 1639.

  Births

January–April

• January 1
• * Tredwell Scudder, American politician
• * Charles Alexandre Lesueur, French naturalist
• January 3 - Antoni Melchior Fijałkowski, Polish Catholic bishop
• January 4
• * Billy J. Clark, American politician
• * Paolo Polidori, Italian Catholic cardinal
• * Jean-Antoine Alavoine, French architect
• January 5 - Charles-Guillaume Étienne, French writer
• January 6 - Thomas Lincoln, Farmer, Carpenter
• January 7 - Anthony Todd Thomson, British dermatologist
• January 9 - Thomas Brown, Scottish metaphysician
• January 10 - Teodoro Sánchez de Bustamante, Argentine politician
• January 11 - Agathon Jean François Fain, French historian
• January 12 - William Herbert, British politician
• January 13 - Sir Isaac Goldsmid, 1st Baronet, British financier and one of the leading figures in the Jewish emancipation in the United Kingdom
• January 15 - Joseph Adamy, Nassauian politician
• January 16
• * Teodoro Lechi, Italian general
• * John Arbuthnott, 8th Viscount of Arbuthnott, Scottish peer and soldier
• January 17
• * Donald Macdonell, Canadian politician
• * George Black, Canadian politician, businessman and important shipbuilder in Quebec, during the earlier part of the 19th century
• January 18 - George Bellas Greenough, British geologist
• January 20 - Louis Antoine François Baillon, French naturalist, collector
• January 21 - Jeremiah O'Brien, American politician
• January 23 - Alire Raffeneau Delile, French botanist
• January 24 - Charles Ferdinand, Duke of Berry, England
• January 25 - Matsudaira Norihiro, Japanese daimyō who ruled the Nishio Domain
• January 26
• * Jakob von Washington, Bavarian general
• * Johann Georg Stauffer, Austrian luthier
• January 27
• * Christian Mathias Schröder, German politician
• * Andrew Sterett, United States Navy officer
• January 28 - James Tallmadge, Jr., American politician
• January 29 - John Williams, Tennessee politician
• January 31 - Franz Anton von Kolowrat-Liebsteinsky, Austrian statesman
• February 1 - Joseph Richardson, American politician
• February 2 - Mary Anne Talbot, British wartime cross-dresser
• February 3
• * Cornelis Vollenhoven, Dutch politician
• * John Ritchie, British newspaper founder
• February 4 - Augustin Pyramus de Candolle, Swiss botanist
• February 5 - Jan Nepomucen Umiński, Polish general
• February 6 - Ugo Foscolo, Italian writer, revolutionary and poet
• February 13 - William P. Van Ness, United States federal judge
• February 14 - Fernando Sor, Spanish musician
• February 16
• * John Colborne, 1st Baron Seaton of Great Britain
• * Rosalie Stier Calvert, 19th century Maryland plantation owner, correspondent
• February 19
• * Friedrich Karl von Tettenborn, Russian military commander
• * Henry Ashley, American politician
• * Daniel Williams Harmon, American-born Canadian fur trader, diarist
• February 22
• * Sir Roger Martin, 5th Baronet of Great Britain
• * Rembrandt Peale, American painter
• February 25 - José de San Martín, Argentine general
• March 1
• * Chrétien Géofroy Nestler, French botanist
• * Amos Lane, American politician
• March 2
• * William Austin, American politician
• * Vincent Moulac, French naval officer
• March 3
• * Princess Frederica of Mecklenburg-Strelitz
• * Peter Laurie, British politician
• March 4
• * Sir Henry Bunbury, 7th Baronet, British Army general
• * Robert Emmet, Irish rebel
• * Florestano Pepe, Italian general
• March 6
• * Francis Ogilvy-Grant, 6th Earl of Seafield, British politician
• * Carl Bernhard von Trinius, German botanist
• March 8 - Jean-Toussaint Arrighi de Casanova, French soldier, diplomat
• March 10
• * Hugh Hornby Birley, leading Manchester Tory, reputed to have led the fatal charge of the Manchester and Salford Yeomanry, at the Peterloo Massacre
• * Anthony Van Egmond, Canadian rebel
• March 19 - Edward Pakenham, Irish-born British general
• March 22
• * Thomas de Trafford, British Baronet
• * Aleksey Merzlyakov, Russian poet, critic, and professor
• March 23 - Paul Traugott Meissner, Austrian chemist
• March 24
• * Robert Fleming Gourlay, British statistician and activist
• * Anton Edler von Gapp, Austrian lawyer
• March 25 - Sophie Blanchard, French aeronaut
• March 26 - Edward Blakeney, British Army officer
• March 28 - Ludvig Stoud Platou, Norwegian politician
• March 30 - Robert Moore, American politician
• March 31 - Coenraad Jacob Temminck, Dutch zoologist
• April 1 - Benjamin Jacob, British musician
• April 3 - Pierre Bretonneau, French physician
• April 7 - John J. Ely, Member of the New Jersey General Assembly
• April 9
• * John Sparks, English cricketer
• * Louis de Beaupoil de Saint-Aulaire, French diplomat
• April 10
• * Heinrich Luden, German historian
• * William Hazlitt, English writer
• * Johann Arzberger, Austrian technologist
• April 12 - John Strachan, Bishop of Toronto
• April 14 - George Philipp Ludolf von Beckedorff, prominent Prussian Catholic convert, parliamentarian
• April 15
• * William Congreve Russell, British politician
• * James Crooks, Canadian politician
• April 18
• * Mary Bruce, Countess of Elgin, Scottish countess
• * Christian Friedrich Nasse, German physician, psychiatrist
• * Sir Matthew White Ridley, 3rd Baronet, British politician
• April 19 - Elizabeth Wynne Fremantle, main author of the extensive Wynne Diaries, wife of Royal Navy officer Thomas Fremantle
• April 23 - John Harvey, British Army general
• April 24 - John Graham, soldier notable for founding Grahamstown
• April 27 - Henry Drury, English educator
• April 28 - Adriaan van der Hoop, Dutch banker, politician
• April 29 - Thomas Bateman, British physician, pioneer in the field of dermatology
• April 30 - Arvid David Hummel, Swedish entomologist