The blazes are threatening Giant Forest, a grove of around 2,000 sequoias that includes five of the largest trees on the planet – some up to 3,000 years old.

The biggest of them all, the General Sherman stands 83 metres (275 feet) tall.

On Thursday, General Sherman was wrapped in fireproof blankets – aluminium foil intended to protect its giant trunk from the worst of the flames.

By Friday, managers felt they had the upper hand, thanks in part to clearing of undergrowth and controlled burns that starve the fire of fuel.

“I think the most challenging part is the terrain here,” said Garrett.

But “we haven’t seen explosive fire behaviour; it really slowed down and gave us a chance to get ahead of it.”

Around 600 personnel are involved in the fight.

“We have folks up in the Giant Forest protecting structures and preparing everything.

“The fact is that they’ve been prescribed burning for the past 25 or 30 years so it is really prepared.”

Millions of acres of California’s forests have burned in this year’s ferocious fire season.

The enormous trees of the Giant Forest are a huge tourist draw, with visitors travelling from all over the world to marvel at their imposing height and extraordinary girth.

While not the tallest trees – California redwoods can grow to more than 300 feet – the giant sequoias are the largest by volume.

Smaller fires generally do not harm the sequoias, which are protected by a thick bark and often only have branches 100 feet above the ground.

But the larger, hotter blazes that are laying waste to the western United States are dangerous to them because they climb higher up the trunks and into the canopy.