A man from Salford has pleaded guilty to scrawling graffiti about Fusilier Lee Rigby's murder on the RAF Bomber Command War Memorial.
Daniel James Smith, 21, of Grecian Street North, admitted writing "Lee Rigby's killers should hang" on the memorial in central London on June 5 - a monument he did not realise was a war memorial.
Colleen Gildernew, defending, said: "He had no idea that the war memorial was a war memorial.
"He is very disgusted with himself, even more so because of that."
Smith also daubed "EDL" and "F*** the police" on the memorial in Green Park, prosecutor Izolda Switala-Gribbin said.
Smith was planning on going to Fusilier Rigby's funeral but was arrested and could not go, Westminster Magistrates' Court heard.
Ms Gildernew said Smith had applied for a job in the British Army but was unsuccessful "because of his convictions as a young boy".
The court heard Smith has 44 convictions and has appeared in different courts five times this year.
Ms Gildernew said the experiences of Smith's two army friends - one who has lost both legs and another who suffers from memory loss as the result of a bomb - had an "emotional impact on him".
The damage to the memorial, which was created to remember the thousands of RAF crew who lost their lives in the Second World War, amounted to £870.
The memorial was vandalised twice in just over a week following the murder of Fusilier Rigby in Woolwich, south east London, on May 22.
District Judge Quentin Purdy described the content of the graffiti inflicted on June 5 by Smith, and its location, as "highly emotive".
He added that Smith's actions clearly challenged the "tolerance we all seek to see in society".
Mr Purdy said people will want to know what the court is doing about people, "brains in gear or not", who inflict such damage.