The 2017 Chartres Pilgrimage Walk Will Fill You with Hope!

The reliquary holding Mary's tunic which
 is carried on the 70-mile Chartres pilgrimage.

The pilgrimage is led by participants carrying the "glory of Chartres," a relic believed to be the tunic Mary wore when she gave birth to the Christ child. Here's an article about its history:

The Veil of the Virgin, or Sancta camisia in Chartres 

"This silk relic kept at Chartres is believed to have been worn by Mary when she gave birth to Jesus. Byzantine Empress Irene of Constantinople sent it as a gift to Charlemagne, whose grandson Charles the Bald donated it to Chartres Cathedral in 876. 

"The presence of the Holy Cloak began the cult of the Virgin at that site, although Chartres was reportedly originally a site dedicated to a pregnant pagan virgin. The Veil of the Virgin is associated with many medieval miracles at Chartres. Through the sancta camisia, Mary is said to have spared Chartres from the invasion of Rollo army. The miracles affected by the holy tunic are often associated with protection of her believers. 

"During a fire in 1145 the church burnt down. A few clerics fled from the flames carrying the shroud into the crypt. They emerged safely after three days, having been sustained miraculously by the intercession of the Virgin. This was declared a miracle by a papal legate, and interpreted as a sign that the Virgin wished for a new and grander church to be built for her veneration, and so the cathedral as it currently stands was built. The cathedral now has stained glass and sculpture that heavily emphasizes the life of the Virgin, and the Sancta camisia now is housed in a reliquary. 

"The Veil of the Virgin gained its sanctity through touching Mary’s body. It was not necessary for there to be any residual breast milk for the tunic to have such power. There were even stories of shirts gaining protective power by touching the chasse of the tunic of the Virgin."