<P> A significant indentation on the middle section of the pillar, approximately 4 m (13 ft) from the current courtyard ground level, has been shown to be the result of a cannonball fired at close range . The impact caused horizontal fissuring of the column in the area diametrically opposite to the indentation site, but the column itself remained intact . While no contemporaneous records, inscriptions, or documents describing the event are known to exist, historians generally agree that Nadir Shah is likely to have ordered the pillar's destruction during his invasion of Delhi in 1739 CE, as he would have considered a Hindu temple monument undesirable within an Islamic mosque complex . Alternatively, he may have sought to dislodge the decorative top portion of the pillar in search of hidden precious stones or other items of value . </P> <P> No additional damage attributable to cannon fire has been found on the pillar, suggesting that no further shots were taken . Historians have speculated that ricocheting fragments of the cannonball may have damaged the nearby Quwwat - ul - Islam mosque--which is known to have suffered damage to its southwestern portion during the same period--and the assault on the pillar might have been abandoned as a result . </P>

The iron pillar at mehrauli in delhi is believed to record the achievement of