A soldier from Worcestershire has been jailed for five years at Worcester Crown Court for the manslaughter of his five-and-a-half-month-old son.
Theo Davies collapsed in 2009 while in the care of Pte Jonathan James, now 25.
Theo died from a head injury and James denied his manslaughter.
Mother Leanne Davies said: "Jonathan James took away the most precious thing in my life and destroyed my world in the 15 minutes it took me to pop out to the shops to buy a pint of milk."
James was found guilty on Thursday after a three-week trial at Worcester Crown Court.
The soldier, who was based at the Ministry of Defence barracks in St Athan, Barry, in the Vale of Glamorgan, called the emergency services when Theo collapsed at his flat in Stourport-on-Severn.
Ms Davies had left the flat to do some shopping at a local store.
Theo was taken to hospital where doctors managed to restart his heart, but he remained unresponsive and he died when care was withdrawn on 26 August 2009.
The prosecution surmised that Pte James lost his temper and violently shook Theo, but said the exact circumstances of what happened might never be known.
In a statement, Ms Davies said: "I never thought he was capable of doing something like that and, as far as I am concerned, he got what was coming to him and deserves to be in prison.
"It plays on my mind that I still don't know exactly what happened to Theo - his father never spoke about what happened that day."