Amazing Grace.

"Amazing Grace" is a well-known Christian hymn. The words were written late in 1772 by Englishman John Newton.
The melody most often used for this hymn was not original. As with other hymns of this period the words were sung to a number of tunes before and after they first became linked to the now familiar variant of the tune "New Britain", in William Walker's shape-note tunebook Southern Harmony 1835.
There are several tunes to which these words have been sung. "New Britain" first appears in a shape note hymnal from 1829 called Columbian Harmony.
The melody is believed to be Scottish or Irish in origin. It is pentatonic and suggests a bagpipe tune. The hymn is frequently performed on bagpipes and has become associated with that instrument. This tune seems to have been firmly established as the 'standard' for this hymn after an arrangement of it appeared in a series of popular hymnbooks in the early twentieth century.
Probably the best known arrangement, particularly in UK, is an instrumental version by the Pipes and Drums and Military Band of the Royal Scots Dragoon Guards, from 1972.