A huge internet campaign sprang up after Brown's bar in Coventry allegedly turned away the pall bearers of city hero Corporal Thacker - including his own brother Matthew - before his funeral.
Hundreds of people flocked to Coventry Cathedral on Monday to say farewell to Michael, who was killed on duty in Afghanistan earlier this month.
After making all the preparations the six pall bearers - including Michael’s brother Matthew - walked round the corner to Browns bar in Jordan Well for tea and coffee.
However, they were turned away by staff for wearing their ceremonial uniforms.
His wife Catherine later posted on the group: “As Cpl Michael Thacker’s wife I have to say when I found out this news I was horrified ,especially seeing as one of the men in uniform was his grieving brother!"
"The lack of respect you have shown my husband, me and the lads yesterday will never be forgotten by the people in Coventry.”
More than 33,000 people have already joined the Facebook group calling for a boycott of Brown's on Saturday, which is Armed Forces Day.
Many are now calling on people to write to Coventry City Council to demand that it revoke the bar's license.
The hashtag #boycottbrowns was also trending on social networking site Twitter.
In creating the Facebook group last night, friends of the fallen soldier wrote: “On Monday June 25, Browns Independent Bar in Coventry refused to serve a group of grieving soldiers, because they were wearing their military uniform, on the day they were burying a brother, Cpl Michael Thacker. Truly disgusting!
“The six pall-bearer’s (and others, including their Commanding Officer) had been rehearsing their duties in the morning before the funeral and had an opportunity to refuel on teas and coffees.