World History · Daily chronology

Pompey, Penicillin and Falcon 1: September 28 Across the Centuries

Nine events connect Rome’s civil wars, a late-antique usurpation, the Norman Conquest, imperial encounters, organized labor, antibiotics, Arab union, maritime safety and commercial spaceflight.

Published Monday, September 28, 2026 at 8:08 a.m. America/New_York · Approximately 12 minutes

Black-and-white portrait of bacteriologist Alexander Fleming — Alexander Fleming, whose 1928 observation of mold inhibiting bacterial growth began the long development path to penicillin therapy. U.S. National Library of Medicine / Wikimedia Commons · Public domain

Chronology note: No securely attested September 28 event was identified for ancient Egypt, Mesopotamia, the Bronze Age or classical Greece. Pompey’s death is conventionally dated September 28, 48 BCE in modern reference works, but converting late Republican Roman dates into a modern calendar is not perfectly secure because Rome’s pre-Julian calendar was irregular. It is therefore presented as the traditional reconstructed date, not modern documentary precision.

48 BCE · Egypt and the Roman Republic · traditional reconstructed date

Pompey is assassinated after fleeing to Egypt

Gnaeus Pompeius Magnus—Pompey the Great—reached Egypt after Julius Caesar defeated him at Pharsalus. Courtiers of the young Ptolemy XIII invited Pompey into a small boat and killed him near the shore, hoping to win Caesar’s favor. Ancient authors turned the murder into a lesson about fortune and civil war: a commander who had celebrated three triumphs died as a refugee, while Egypt’s dynastic struggle became entangled with Rome’s. Caesar’s subsequent intervention placed him at the center of the conflict between Ptolemy and Cleopatra VII and accelerated the collapse of the Roman Republic’s old political order.

365 · Constantinople · late antiquity

Procopius is proclaimed emperor against Valens

With Emperor Valens away from Constantinople, the official and military commander Procopius persuaded two passing legions to proclaim him emperor on September 28, 365. Related to the Constantinian dynasty, he used that connection, coinage and control of communications to build support in Thrace and Bithynia. His regime lasted only months: Valens defeated him and had him executed in May 366. The revolt nevertheless exposed the importance of dynastic legitimacy, army loyalty and possession of the imperial capital in the fourth-century Roman world.

1066 · England

William of Normandy lands at Pevensey

William’s invasion fleet reached Pevensey on the Sussex coast on September 28, 1066, after crossing the Channel overnight. The Normans established temporary defenses inside the surviving Roman fort before moving toward Hastings. King Harold II was still returning from victory over a Norwegian invasion in Yorkshire. William’s landing thus opened the final campaign in a three-sided succession crisis. His victory at Hastings on October 14 led to a new ruling elite, extensive land redistribution, castle building and major changes in English government, church organization and language.

1542 · Kumeyaay homeland and New Spain

Cabrillo’s expedition enters San Diego Bay

Three vessels commanded by Juan Rodríguez Cabrillo entered the harbor now called San Diego Bay on September 28, 1542, during a Spanish expedition sailing north from Mexico. Cabrillo named it San Miguel. The landing is often described as the first recorded European arrival on the future United States’ Pacific coast, but it was not the beginning of the region’s history: the Kumeyaay had lived around the bay for thousands of years and encountered the expedition from within an established homeland. The voyage extended Spanish geographic knowledge and foreshadowed later imperial claims, missions and colonization.

1864 · London

Workers establish the First International

Trade unionists, socialists and political émigrés from several European countries met at St Martin’s Hall in London on September 28, 1864, and founded the International Working Men’s Association, later called the First International. Karl Marx joined its General Council and drafted its inaugural address, but the association contained competing traditions, including trade unionists, republicans, followers of Pierre-Joseph Proudhon and later anarchists associated with Mikhail Bakunin. It never became a unified world party. Its importance lay in creating a durable model for labor movements to coordinate across national borders.

1928 · London · customary discovery date

Fleming recognizes the antibacterial effect that led to penicillin

September 28 is widely commemorated as the day Alexander Fleming noticed that mold contaminating a staphylococcus culture had created a bacteria-free zone. The surviving laboratory chronology supports late September 1928 but does not make the single day as certain as the traditional anniversary suggests. Fleming named the active substance penicillin and published his findings, yet he did not turn it into a practical medicine alone. A later Oxford team led by Howard Florey and Ernst Chain developed purification, testing and production methods; wartime collaboration then enabled mass manufacture. The achievement was a chain of observation, experimentation and engineering rather than one isolated eureka moment.

1961 · Syria and Egypt

A military coup ends Syria’s union with Egypt

Syrian officers seized power on September 28, 1961, and withdrew Syria from the United Arab Republic, the union it had formed with Egypt in 1958. Supporters of Arab unity had imagined a larger political community led by Gamal Abdel Nasser, but Syrian resentment grew over centralized rule from Cairo, military reorganization and economic policy. The secession restored the Syrian Arab Republic while Egypt retained the United Arab Republic name until 1971. It demonstrated the strength of pan-Arab aspirations—and the difficulty of reconciling them with distinct state institutions and political interests.

1994 · Baltic Sea

The passenger ferry Estonia sinks

The roll-on/roll-off passenger ferry Estonia capsized and sank in severe weather during the night of September 27–28, killing 852 people. Investigators concluded that the bow visor failed, allowing water onto the vehicle deck, where the open space let flooding rapidly destabilize the ship. The scale and speed of the disaster transformed international attention to ro-ro ferry vulnerabilities. The International Maritime Organization subsequently strengthened stability, evacuation and safety requirements, although debate over aspects of the loss has continued for decades.

2008 · Kwajalein Atoll and Earth orbit

Falcon 1 becomes the first privately developed liquid-fueled rocket to reach orbit

SpaceX successfully launched Falcon 1 from Omelek Island on September 28, 2008, after three failed attempts. NASA’s historical chronology identifies it as the first privately developed and funded rocket to achieve orbit. The small vehicle did not immediately transform launch markets, and its demonstration payload remained attached to the second stage, but the flight proved the company’s core launch capability. It helped establish a path toward Falcon 9, commercial cargo service to the International Space Station and a much larger private role in orbital transportation.

Across the centuries

Turning points depend on systems, not isolated moments

Pompey’s murder mattered because it redirected a civil war; Procopius and William depended on armies, legitimacy and control of strategic places. Cabrillo’s voyage became consequential through later empire, while international labor required organization across borders. Penicillin reached patients only through years of collective development, ferry loss produced regulatory change, and Falcon 1 became significant through the launch system that followed it. The date links dramatic moments to the institutions that magnified their effects.

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