How the Great Fire of London Spread

Figure 1: Approximate buildings destroyed per day during the Great Fire, based on historical estimates from the Museum of London and contemporary accounts. Numbers are approximate.

01 The City That Was Waiting to Burn

London in 1666 was a medieval city that had outgrown its infrastructure. The Roman wall that once contained it now trapped a dense warren of timber-framed buildings, many six or seven stories high, jutting over narrow streets so that neighbors on opposite sides could nearly shake hands from upper windows. The streets themselves were barely wide enough for a cart, and many were lined with pitch, tar, and timber yards — the combustible raw materials of a city still largely built from wood.

The preceding summer had been one of the hottest and driest on record. Rain had been scarce for months, turning the city's predominantly wooden structures and their thatched roofs into kindling. The Thames, which served as both the city's primary water source and its main thoroughfare, was at a low ebb. Firefighting in 1666 meant leather buckets, hand-operated syringes, and gunpowder demolition — tools designed for small house fires, not urban conflagrations.

02 Pudding Lane: The Spark

Shortly after midnight on Sunday, September 2, 1666, a fire broke out in the bakery of Thomas Farriner, the king's baker, on Pudding Lane. Farriner had failed to properly extinguish his oven before retiring for the night, a routine task but one that carried lethal consequences in a city built of seasoned timber. Sparks from the smoldering oven reached the adjacent fuel — firewood, flour dust, and the wooden structure itself — and the blaze took hold rapidly.

The household was trapped. Farriner, his daughter, and a maidservant escaped through an upstairs window onto a neighboring roof. Another maidservant was too frightened to climb and became the fire's first recorded casualty. By the time the first watchmen arrived, flames had already consumed the bakery and were climbing the adjacent buildings. The narrow lane — only about 16 feet wide at its narrowest — acted as a chimney, funneling heat upward and feeding oxygen to the growing fire.

03 The Wind That Devoured a City

What turned a bakery fire into a city-destroying catastrophe was an unusually strong easterly wind. For three days, winds blowing from the east drove the fire westward through the city's dense heart — the opposite of the prevailing southwesterly winds that London typically experienced. This meant the fire advanced faster than firefighters could respond, and the sparks and embers it cast ahead ignited new fires blocks in advance of the main front.

The wind carried burning debris across streets that might otherwise have served as firebreaks. Embers landed on rooftops far ahead of the fire's leading edge, creating spot fires that rapidly merged into a continuous front. The city's narrow streets, far from providing breaks, instead functioned as wind tunnels that accelerated the spread. Contemporary accounts describe flames leaping entire streets, a phenomenon consistent with the extreme ember-casting behavior documented in modern fire science.

04 The Path of Destruction

The fire spread in a roughly westward and northward arc from Pudding Lane. On the first day, it consumed the riverside warehouses around Fish Street Hill and Bridge Street, where stores of pitch, tallow, oil, hemp, and coal provided enormous fuel loads that generated intense heat and thick smoke. The fire then advanced along Thames Street, consuming the wharves and warehouses that formed the commercial backbone of the city.

By Monday, September 3, the fire had reached the heart of the City. Flames engulfed Cheapside, one of London's busiest commercial streets, and threatened the Royal Exchange. St. Paul's Cathedral, whose old medieval structure had been crumbling and whose scaffolding was undergoing repairs, was surrounded by the fire. The scaffolding itself became a bridge for flames to reach the wooden roof beams. The cathedral's lead roof melted and flowed into the streets like rivers of molten metal — contemporary accounts described it running through the gutters.

Figure 2: Key events timeline of the Great Fire from the initial bakery blaze to containment. Dates and events compiled from contemporary accounts and the Museum of London.

05 Firebreaks and Gunpowder

The primary firefighting strategy of the era was demolition — pulling down buildings ahead of the fire to create empty gaps it could not cross. This was slow, laborious, and often too late. By the time workers pulled down a row of houses, the fire had already advanced past the intended break. Mayor Sir Thomas Bloodworth, whose initial response was famously lethargic — he reportedly dismissed the early blaze with the words "a woman might piss it out" — was slow to order demolitions and slower still to command the use of gunpowder.

Gunpowder demolition, in which buildings were blown up rather than pulled down by hand, proved far more effective at creating wide firebreaks. The Royal Navy, commanded by the king's brother James, Duke of York, brought sailors with expertise in explosives to apply this technique at scale. Wide gaps were blasted along the city's western edge, and by the evening of Tuesday, September 5, the fire had largely exhausted its fuel supply and been contained. The wind had also begun to ease, removing the relentless driving force that had carried the flames westward.

06 The Toll and the Reckoning

When the smoke cleared, the scale of destruction was staggering. The fire had consumed an area approximately 1.5 miles long and 0.5 miles wide — roughly 80 percent of the walled City of London. Approximately 13,200 houses, 87 parish churches, 44 livery company halls, the Royal Exchange, the Custom House, St. Paul's Cathedral, and numerous other public buildings were destroyed. An estimated 70,000 of the 80,000 City residents were left homeless.

The official death toll was recorded as just six people, a figure that has long been questioned. The intense heat of the fire — capable of melting lead and iron — likely cremated many victims beyond recognition, and the chaos of displacement meant many deaths went unrecorded. Modern historians have suggested the true toll may have been in the hundreds or even thousands. The fire also caused massive economic disruption, destroying commercial records, debts, and property records that shaped London's financial landscape for decades.

07 Rebuilding and Legacy

The Great Fire fundamentally reshaped London. Rebuilding was rapid but initially disappointingly conservative — Charles II and city leaders proposed ambitious plans with wide boulevards and stone buildings, but property rights and the urgent need to restore commerce meant the city was largely rebuilt along its old medieval street pattern. The critical change was building regulations: the 1667 Rebuilding Act mandated brick and stone construction, wider streets in some areas, and standardized building heights. Fireproof materials replaced the timber and thatch that had made London so vulnerable.

The fire's legacy extended well beyond building codes. The Monument, a 202-foot Doric column designed by Christopher Wren and Robert Hooke, was erected near Pudding Lane to commemorate the disaster. The insurance industry was effectively born in the fire's aftermath, as Nicholas Barbon established the first fire insurance company in 1667. The city that emerged from the ashes was still recognizably London, but it was a city that would never again be built primarily of wood — a lesson written in char and ash that every subsequent generation of urban planners has carried forward.