So, Francis Cassidy son of Patrick and Ann Stafford looks to be the Francis who died in WW1/1916.
The reference to Longford certainly comes up for him too I think.
This is the family in Glasgow in 1891:
Patrick Cassidy 31 Furnace Stoker Tube Work b. Ireland
Ann Cassidy 32 b. Ireland
Robert Cassidy 9 b. Ireland
George Cassidy 6 b. Ireland
Francis Cassidy 4 b. Ireland
Patrick Cassidy 2 b. Ireland
Kate Cassidy Under 1 Month b. Glasgow
Mary Stafford 18 river maker, sister in law, b. Ireland
Address: 18 Grace St, Anderston/Glasgow
One of the children's births in Longford
https://familysearch.org/ark:/61903/1:1:FG2Z-JF6 and youngest's details here
https://familysearch.org/ark:/61903/1:1:XTFQ-JFWThe family show as living at 37 Albert Street Govan by 1901.
Monica