Ciaran Maxwell, a Royal Marine from Exminster, has been sentenced to 18 years in prison.
Maxwell was arrested in Somerset last August after the discovery of two major arsenals of weapons hidden in Northern Ireland.
An investigation found that the 31-year-old stashed anti-personnel mines, ammunition and 14 pipe bombs - four of which were deployed - in 43 purpose-built hides at eight locations in Northern Ireland and Devon.
Bomb-making materials were found in barrels and buckets buried in the ground as well as an adapted Police Service of Northern Ireland (PSNI) pass card, a PSNI uniform and a stab-proof vest.
Maxwell who is originally from Larne in Co Antrim, plead guilty in February to preparation of terrorist acts between January 2011 and August last year, possessing images of bank cards for fraud and possessing cannabis with intent to supply.
Maxwell, of Exminster in Devon, was a serving Royal Marine with 40 Commando based at Norton Manor Camp in Taunton at the time of the offences and was deployed in the United States, Cyprus and the UK - but not Northern Ireland - after enlisting in 2010.