Drewe Broughton and Davide Somma had both tested Frank Fielding in the Rochdale goal before the Imps took the lead in the 27th minute.
Cian Hughton's low cross into the middle was controlled by Somma and he turned to see Chris Herd unmarked on the left side of the area who stroked home.
Dagnall had Rochdale's best effort of the first half with a stinging drive that Rob Burch pushed round the post.
After the break the hosts turned up the heat on Lincoln's backline and he pressure finally told in the 69th minute when Dagnall wriggled free of two defenders and his deflected shot squirmed past Burch.
Source: Team Talk
Source: Team Talk