Former Army veteran Stewart Williamson lost control of his car which ploughed into grandfather Eduard Goudsblom who was then trapped under the vehicle on April 6 last year.
A judge told Williamson, 55, the victim was "irreplaceable" and Mr Goudsblom's widow had said "the joy has gone from her life".
John Beckett QC told the security consultant at the High Court in Edinburgh: "You made the incomprehensible decision to drive home when you had been drinking for several hours."
The judge pointed out Williamson's car was partly off the road in Pitlochry when it struck the 70-year-old retired care home manager, from Zetten, in the Netherlands.
Mr Beckett told Williamson: "I note you served this country in the armed forces for more than 20 years and your service was exemplary."
The judge added: "I accept you have expressed and felt genuine remorse."
He said there was significant mitigation in his personal circumstances and in the remorse he had shown.
The judge told Williamson he would have faced a seven-year prison sentence but for his guilty plea and also banned him from driving for seven years and ordered he sit a test again.
Williamson, of Duff Avenue, Moulin, Pitlochry, previously admitted causing the death of Mr Goudsblom by driving dangerously while under the influence of alcohol.