In 2014, the moat was filled with 888,246 red poppies to mark the centenary of World War One breaking out.
This year, which will mark 100 years since the Armistice, the Tower of Londons moat has been filled with around 10,000 lit torches.
Each night until Remembrance Sunday, the spectacle will be repeated in tribute to those whose lives were affected by war: not only people who died, but those left behind.
This evening was the first showing, beginning with a ceremonial Beefeater guard bringing a flame down from the tower into the moat, which had been submerged in smoke.
Dozens of representatives from the armed forces and volunteers then used the flame to ignite thousands of other torches staked into or placed on the ground underneath the tower, bathing the moat in light.
Midshipman Balraj Dhanda of the Royal Navy, a volunteer who helped light the flames, described the spectacle as really, really powerful.
I think it creates the right atmosphere for people to have their own personal reflections and gives people time with their own thoughts, he added.
It took around 45 minutes to light the flames, which then burn for roughly four hours.
The ceremony was accompanied by a specially commissioned sound installation featuring choral music, as well as words from war poet Mary Bordens Sonnets To A Soldier.
The ceremony was amazing, according to Dick Harrold, governor of the Tower of London.
He added: What is so special about it is it means many different things.
The message with the sound is not focused so much on those that were lost, but those that were left behind, the bereaved and others who were affected by war.
The success of the 2014 display of poppies at the tower meant Historic Royal Palaces, who maintain the landmark, were keen to mark the centenary of Armistice.
He added: But, of course, we couldnt do poppies again.
Spectators gathered on vantage points around the tower to witness the spectacle.
A minutes silence was also observed.
The ceremony, named Beyond The Deepening Shadow, will be repeated each night until the final showing on Remembrance Sunday.
Members of the public can watch the spectacle for free.