 William Hulton , the chairman of the magistrates watching from the house on the edge of St Peter 's Field , saw the enthusiastic reception that Hunt received on his arrival at the assembly , and it encouraged him to action . He issued an arrest warrant for Henry Hunt , Joseph Johnson , John Knight , and James Moorhouse . On being handed the warrant the Chief Constable , Jonathan Andrews , offered his opinion that the press of the crowd surrounding the hustings would make military assistance necessary for its execution . Hulton then wrote two letters , one to Major Thomas Trafford , the commanding officer of the Manchester and Salford Yeomanry Cavalry , and the other to the overall military commander in Manchester , Lieutenant Colonel Guy L 'Estrange . The contents of both notes were similar : 
