In this artwork, how is the Damage and restorations of the History elucidated?

Because Sforza had ordered the church to be rebuilt hastily, the masons filled the walls with moisture-retaining rubble. The painting was done on a thin exterior wall, so the effects of humidity were felt keenly, and the paint failed to properly adhere to it. Because of the method used, soon after the painting was completed on 9 February 1498 it began to deteriorate. In 1499, Louis XII contemplated removing the painting from the wall and taking it to France. As early as 1517, the painting was starting to flake, and in 1532 Gerolamo Cardano described it as "blurred and colorless compared with what I remember of it when I saw it as a boy". By 1556 – fewer than sixty years after it was finished – Giorgio Vasari described the painting as reduced to a "muddle of blots" so deteriorated that the figures were unrecognizable. By the second half of the 16th century, Gian Paolo Lomazzo stated that "the painting is all ruined". In 1652, a doorway was cut through the (then unrecognisable) painting, and later bricked up; this can still be seen as the irregular arch-shaped structure near the center base of the painting. It is believed, through early copies, that Jesus' feet were in a position symbolizing the forthcoming crucifixion. In 1768, a curtain was hung over the painting intended for its protection; the curtain instead trapped moisture on the surface, and whenever it was pulled back, it scratched the flaking paint.
A first restoration was attempted in 1726 by Michelangelo Bellotti, who filled in missing sections with oil paint then varnished the whole mural. This repair did not last well and another restoration was attempted in 1770 by an otherwise unknown artist named Giuseppe Mazza. Mazza stripped off Bellotti's work then largely repainted the painting; he had redone all but three faces when he was halted due to public outrage. In 1796, French revolutionary anti-clerical troops used the refectory as an armory and stable; they threw stones at the painting and climbed ladders to scratch out the Apostles' eyes. Goethe wrote that in 1800, the room was flooded with two feet of water after a heavy rainstorm. The refectory was used as a prison; it is not known if any of the prisoners may have damaged the painting. In 1821, Stefano Barezzi, an expert in removing whole frescoes from their walls intact, was called in to remove the painting to a safer location; he badly damaged the center section before realizing that Leonardo's work was not a fresco. Barezzi then attempted to reattach damaged sections with glue. From 1901 to 1908, Luigi Cavenaghi first completed a careful study of the structure of the painting, then began cleaning it. In 1924, Oreste Silvestri did further cleaning, and stabilised some parts with stucco.During World War II, on 15 August 1943, the refectory was struck by Allied bombing; protective sandbagging prevented the painting from being struck by bomb splinters, but it may have been damaged by the vibration. Between 1946 and 1954, Mauro Pellicioli undertook a clean-and-stabilise restoration, which Brera director Fernanda Wittgens was involved in. Pellicioli reattached paint to the wall using a clear shellac, making it relatively darker and more colorful, and removed some of the overpainting. However, as of 1972, the repainting done in various restorations had made the heads of saints Peter, Andrew, and James differ significantly from the original design.
Jesus Louis XII Sforza glue refectory overpainting Gerolamo Cardano Oreste Silvestri armory varnish Gian Paolo Lomazzo Michelangelo Bellotti Luigi Cavenaghi World War II vibration Brera Leonardo Giorgio Vasari humidity Goethe Andrew arch 1972 Mauro Pellicioli stucco stable mural oil paint Michelangelo sandbag Peter Fernanda Wittgens