France's President Emmanuel Macron, right, and French Armies Chief Staff General Francois Lecointre, left, stand in the command car as they review troops before the start of the Bastille Day military parade last year
The open letter, published in Valeurs Actuelles, a right-wing magazine, claims a military coup might be necessary to stop a 'civil war' in France.
Despite condemnation from the government and left-wing parties, Marine Le Pen hailed the letter which was signed by 80 officers, as well as the 20 generals.
'I invite you to join us in taking part in the coming battle, which is the battle of France,' she wrote in a response to the letter.
Le Pen was widely criticised by her opponents on both the left and right for her overtures to the soldiers behind what the left-wing daily Liberation described as a 'call to sedition'.
The lead signatory was Christian Piquemal, 80, who commanded the Foreign Legion before losing his privileges as a retired officer after being arrested while taking part in an anti-Islam demonstration in 2016.
It was written by Jean-Pierre Fabre-Bernadac, a former officer, and signed by 1000 others who were in lower ranks.
The incendiary letter reads: 'France is in danger. Several mortal perils threaten her. Even in retirement, we remain soldiers of France and cannot in the present circumstances remain indifferent to the fate of our beautiful country.'
The retired officers claimed that France was 'disintegrating with the Islamists of the hordes of the banlieue [suburbs] who are detaching large parts of the nation and turning them into territory subject to dogmas contrary to our constitution'..
They also claimed they had broad support in the military and were 'ready to support' politicians who focused on the 'safety of a nation'.
Le Pen's National Rally gave the letter their backing, saying it reflected the views of 'patriots' like General Pierre de Villiers, former chief of the defence staff, who was sacked by Macron in 2017.
