Incredible accounts of the Welsh Methodist revival. I learned of these through Iain Murray's accounts of Martyn Lloyd-Jones and his love affair with Welsh church history including these volumes.
The book takes several of the Welsh Methodists who were really more Calvinistic and Presbyterian than Wesleyan and shines a huge spotlight on the sovereign work of the Lord amongst them as he brought entire regions of Wales under the dominion of Christ and his kingdom through 'exhorters' with little to no formal theological training.
(Note that so far I've only read the second volume).
This book takes you on a real journey!
North Wales had so many powerful preachers and pray-ers. God worked wonderfully in those days through such legends as John Elias, Robert Roberts, Thomas Charles, Thomas Jones, Ebenezer Morris, John Evans. Oh for more of that 'Welsh fire'!