There were not stamps in 1803. The date must be referencing something about Robert Emmet. Stamps were not available until 1840.
Robert Emmet died on 1803-09-20.
Robert emmet
Are you looking for specific people who were executed on the same day as Emmet? Or are you just looking for all who were executed in connection with the 1803 Rebellion?
The Treaty was dated 30 April 1803 and signed on 2 May 1803.
Robert Rutherford died in 1803.
Robert Jephson died in 1803.
Robert Allwood was born in 1803.
Robert Dulhunty was born in 1803.
Robert Scott Lauder was born in 1803.
Robert J. Kleberg was born in 1803.
Carl Robert Ehrström was born in 1803.
Robert Wellbeloved Scott was born in 1803.