Cassidy scored the winning goal in the 1934 Football League Third Division North Cup Final as Darlington came back from a two-goal deficit to beat Stockport County 4–3 at Old Trafford, Manchester.
According to the Manchester Guardian's report,A succession of corner-kicks was gained by Darlington, and from one of these Best headed another equalising goal.
Then, when the referee had his watch in his hand, Cassidy dribbled through the Stockport defence, and he had no sooner shot the ball into the net than the whistle sounded for the finish of the match.
[6]His father, also named Daniel Cassidy, was a shipyard labourer born in Derry, Ireland.
This biographical article related to association football in England, about a midfielder born in the 1900s, is a stub.