Laden with 150 kg (330 pounds) of bricks each, the seven animals finally got moving in response to the coaxing and swearing of their masters, eager to gain altitude before the sun climbed high in the sky.
For more than a decade, mules have been crucial in the effort to restore Jiankou, a serpentine 20-km (12-mile) section of the wall about 70 km (44 miles) north of central Beijing that is notorious for its ridges and perilous slopes.
Where they could, workers used the original bricks that had broken off the wall over the centuries. When they found none, they used new bricks made to exacting specifications.
"We have to stick to the original format, the original material and the original craftsmanship, so that we can better preserve the historical and cultural values," said Cheng Yongmao, the engineer leading Jiankou's restoration.
Cheng, 61, who has repaired 17 km (11 miles) of the Great Wall since 2003, belongs to the 16th generation in a long line of traditional brick makers.
If he ran out of bricks, Cheng added, he would have to look for bricks left elsewhere or request the central government to consider reopening some brick factories.
Concrete Pavement
Famed for its rugged beauty, Jiankou, which is Chinese for an arrow's nock, or notch for a bowstring, was built in the twilight years of the Ming dynasty in the 1600s, but is young compared with other sections dating back two millennia.
Intensive repairs on the Jiankou section in the past year have been led by the district government keen to preserve the wall's natural beauty and shore up its disintegrating steps.
The restoration began in 2005 and is now in its third phase, making slow progress because the uneven terrain allows use only of basic tools such as chisels, hammers, pickaxes and shovels.
Authorities' meticulous approach followed widespread outrage last year sparked by botched restoration efforts on some stretches.
Soon after, the State Administration of Cultural Heritage said it would investigate any improperly executed wall preservation projects.
Just a tenth of the wall built during the Ming dynasty has been repaired, said Dong Yaohui, vice president of the China Great Wall Association.
"In the past, we would restore the walls so that they would be visited as tourist hot spots," he said, by contrast with today's objective of repairing and preserving them for future generations. "This is progress."