Lucas is born in Druminargal House, Poyntzpass, County Armagh, in what is now Northern Ireland, on February 19, 1834. He enlists in the Royal Navy in 1848 at the age of 13, serves aboard HMS Vengeance, and sees action in the Second Anglo-Burmese War of 1852–53 aboard the frigate HMS Fox at Rangoon, Pegu, and Dalla. By age 20, he has become a mate.
On June 21, 1854 in the Baltic Sea during the Crimean War, HMS Hecla, along with two other ships, is bombarding Bomarsund, a fort in the Åland Islands off Finland. The fire is returned from the fort and, at the height of the action, a live shell lands on HMS Hecla‘s upper deck with its fuse still hissing. All hands are ordered to fling themselves flat on the deck, but 20-year-old Lucas with great presence of mind runs forward and hurls the shell into the sea where it explodes with a tremendous roar before it hits the water. Thanks to his action no one on board is killed or seriously wounded by the shell and, accordingly, he is immediately promoted to lieutenant by his commanding officer. His act of bravery is the first to be rewarded with the Victoria Cross in 1857.
In 1879 Lucas marries Frances Russell Hall, daughter of Admiral William Hutcheon Hall, who had been captain of HMS Hecla in 1854. The couple has three daughters together. Lucas serves for a time as Justice of the Peace for both Kent and Argyllshire.
Lucas’s later career includes service on HMS Calcutta, HMS Powerful, HMS Cressy, HMS Edinburgh, HMS Liffey and HMS Indus. He is promoted to commander in 1862 and commands the experimental armoured gunboat HMS Vixen in 1867. He is promoted to captain in 1867, before retiring on October 1, 1873. He is later promoted to rear admiral on the retired list in 1885. During his career he receives the India General Service Medal with the bar Pegu 1852, the Baltic Medal 1854–55, and the Royal Humane Society Lifesaving Medal.
Lucas’s campaign medals, including his Victoria Cross, are displayed at the National Maritime Museum in Greenwich, London. They are not the original medals, which were left on a train and never recovered. Replacement copies were made, though the reverse of the Victoria Cross copy is uninscribed.