As his boat approached San Francisco, Leach took in "a terrible sight....Great clouds of black smoke...hid the rays of the sun. Buildings in the track of the rapidly spreading fire went down like houses of cardboard." The mint was just 12 blocks up Market Street from the ferry terminal, normally a 20-minute walk. But when he disembarked, Leach found Market Street to be "a mass of flames," so he was forced to circle north to skirt the devastation. Finally, perhaps 90 minutes after arriving in San Francisco, Leach reached Market and Powell, today the downtown terminus of the Fisherman's Wharf cable car line. There soldiers blocked his path, ignoring his pleas until, at last, a police officer recognized him and personally escorted him to the mint.
When Leach arrived, he found the mint employees and the ten soldiers going "about the work in a simple, every-day manner, but nevertheless with earnest, willing, and active spirit. I felt proud to be Superintendent of that band of faithful and brave men." He applauded Hawes’ "excellent judgment": the decision to move everything flammable from around the doors and windows had prevented the small fires in the immediate vicinity from entering the Granite Lady.
But in the distance, flames were larger and growing. Leach divided the men into squads, positioning them on all four floors and on the roof, and instructed them to douse the building's interior with water, especially its window frames and mahogany woodwork. Wherever the hoses couldn't reach, he organized bucket brigades.
At 1 p.m., Leach surveyed the city from the mint’s roof. "Our position look[ed] rather perilous," he later wrote in a memoir. "It did not seem probable that the structure could withstand the terrific mass of flames that was sweeping down upon us." If he had to abandon the mint, to "preserve the lives of the brave men defending the property," his plan was to retreat south, where many tenements had already burned. He could see that the area was charred wreckage—still hot, but cooling and, he thought, passable.
Suddenly, the fire was upon them: "Inside, the building was made almost dark as night by a mass of black smoke that swept in upon us just ahead of the advancing flames," Leach wrote. Then came "a tremendous shower of red hot cinders that fell on our building as thick as hail, and piled up on the roof in drifts nearly two feet deep...for a distance of twenty feet." Sparks and cinders fell on wood lying in the building's central courtyard, starting "a dozen little fires." Flames had finally breached the mint's walls.
Leach and his men knew that if they failed to contain the fires in the courtyard, the mint would be lost. But as soon as they extinguished one blaze, the rain of cinders ignited another. "I show[ed] a soldier who was handling one line of hose how to get the most efficiency from the stream of water," Leach later recalled. Almost immediately, burning cinders scorched their clothes.
Sometime in the afternoon, their luck turned: probably because of a shift in wind, the hail of burning cinders abated. By this time, the men had drenched everything in the courtyard, so Leach sent them to the mint's upper floors, where, he wrote, "the hardest struggle against the flames would soon take place."
The mint's north side faced a narrow alley; across it, everything was ablaze. "Great masses of flame shot against the side of our building," Leach wrote, "as if directed against us by a huge blow-pipe." The new fire hoses that had appeared so powerful just days earlier now looked as puny as squirt guns. The heat was so intense that "the glass in our windows," Leach continued, "did not crack and break, but melted down like butter." Joe Hammill observed, "We were prisoners and fighting for our lives."
Stone heated to high temperatures produces popping sounds, and the mint's enormous mass of granite and sandstone created what Harold French described as "thunder" like "the deafening detonations" of "thirteen-inch shells against the walls." Leach noted that "at times the concussions from the explosions were heavy enough to make the floor quiver."
With glass melted out of so many windows, Leach watched as "great tongues of flame" darted into the building, setting the interior woodwork ablaze. With the hose and buckets in relays, the men "dashed into the rooms to play water on the flames," Leach recalled. The men stayed in the rooms, which Leach called "veritable furnaces," for "as long as they could hold their breaths," and "then came out to be relieved by another crew of willing fighters." Joe Hammill remembered that "we stuck to the windows until they melted, playing a stream of water on the blazing woodwork. Then, as the flames leaped in and the smoke nearly choked us, we were ordered downstairs." So far, the mint's treasure lay safe in its basement vaults. But now, Hammill wrote, "It [appeared] the Mint was doomed."