[1]: 425–427 As a leading figure in the Irish Republican Brotherhood (also known as IRB and Fenians), Flood was centrally involved in some of the major actions of the 1860s.

[2] Flood's first prominent role was as part of the 14-man team that engineered the escape of Fenian founder James Stephens from the Richmond Bridewell in Dublin in November 1865.

Along with a childhood friend, Captain Nicholas Weldon, Flood smuggled Stephens out of Dublin harbour past the revenue cutters by boat to Scotland, then overland to London and across the English Channel to France.

Flood was appointed Head Centre of the IRB in England and Scotland, and concentrated on shipping rifles and ammunition from the USA to Ireland.

[4] Flood and his shipmates passed the voyage to Fremantle publishing a handwritten newspaper named The Wild Goose after the Irishmen exiled to continental armies in the sixteenth century.

The paper ceased publication in August 1872, and Flood set off fortune hunting in the Palmer River goldfield in far north Queensland.

[1]: 428–429 After two years of struggling to make his fortune Flood decided to cut his losses and retreat to the port of Cooktown, 130 kilometres (81 mi) away.

Michael Davitt had been a central figure in the plan to raid Chester Castle, but evaded capture until 1870 so did not join Flood and the others on the Hougoumont bound for Western Australia.

It is engraved with a round tower, an Irish wolfhound and the national harp of Ireland and includes inscriptions to Flood, his wife and their deceased children.