holy of holies would be desecrated by fire. Listen to what happened.

To the sound of a heavy rifle-fire, designed to frustrate all efforts
at extinguishing the dread fire-demon, the flaming torch was applied
by Chinese soldiery to half a dozen different places, and almost
before anybody knew it, the holy of holies was lustily ablaze. As the
flames shot skywards, advertising the danger to the most purblind,
everybody at last became energetic and sank their feuds. British
marines and volunteers were formed up and independent commands rushed
over from the other lines; a hole was smashed through a wall, and the
mixed force poured raggedly into the enclosures beyond. They had to
clamber over obstacles, through tightly jammed doors, under falling
beams, occasionally halting to volley heavily until they had cleared
all the ground around the Hanlin, and found perhaps half a ton of
empty brass cartridge cases left by the enemy, who had discreetly
flown. From a safe distance snipers, hidden from view an untraceable,
kept on firing steadily; but they were careful not to advance.

Meanwhile the flames were spreading rapidly, the century-old beams and
rafters crackling with a most alarming fierceness which threatened to
engulf the adjacent buildings of the Legation. What huge flames they
were! The priceless literature was also catching fire, so the
dragon-adorned pools and wells in the peaceful Hanlin courtyards were
soon choked with the tens of thousands of books that were heaved in by
many willing hands. At all costs this fire must be checked. Dozens of
men from the British Legation, hastily whipped into action by sharp
words, were now pushed into the burning Hanlin College, abandoning
their tranquil occupation of committee meetings and commissariat work,
which had been engaging their attention since the first shots had been
fired on the 20th, and thus reinforced the marines and the volunteers