St Manchen founded a monastery at Lemanaghan Co Offaly not far across the great bog of Offaly to Clonmacnoise. Other details are not clear because there were at least five more Manchens. It appears St Ciaran sent St Manchen to evangelise, which he did and founded the monastery in the process. His mother was St Mella who lived in solitude in a little oratory that can still be found behind the church at Lemanaghan. The holy well is famous for its cures.
St Manchen died of the yellow plague. His glory is reflected in the intact beautiful shrine made in 1130 kept in the church in Boher and which still contains some of his bones.