An end-port regenerative furnace, comprising: a housing; a combustion chamber disposed within the housing; a charging end associated with the combustion chamber; a first port and a second port at the housing for communication with the combustion chamber at the charging end; a discharging end associated with the combustion chamber and spaced apart from the charging end; a first regenerator disposed at the charging end and in communication with the combustion chamber through the first port, the first regenerator adapted for cyclical operation between a firing mode wherein fuel is injected proximate preheated combustion air passing through the first port into the combustion chamber, and an exhaust mode wherein products of combustion are exhausted from the combustion chamber through the first port; a first lance assembly (20, 28) disposed only in the half of the combustion chamber closest to the discharging end and adapted for cyclical operation between a fuel gas mode in which it injects only fuel gas and an oxygen mode in which it injects only oxygen concurrent with the cyclical operation of the first regenerator; a second regenerator disposed at the charging end and in communication with the combustion chamber through the second port, the second regenerator adapted for cyclical operation between the firing mode wherein fuel is injected proximate preheated combustion air passing through the second port into the combustion chamber, and the exhaust mode wherein products of combustion are exhausted from the combustion chamber through the second port; and a second lance assembly (22, 30) disposed only in the half of the combustion chamber closest to the discharging end and adapted for cyclical operation between a fuel gas mode in which it injects only fuel gas and an oxygen mode in which it injects only oxygen concurrent with the cyclical operation of the second regenerator; wherein the first lance assembly (20, 28) is operable in a fuel gas mode concurrently with the firing mode of the first regenerator to provide fuel rich combustion and a fuel rich combustion product flow within the combustion chamber, and the second lance assembly (22, 30) is operable in an oxygen mode concurrently with the exhaust mode of the second regenerator to provide additional oxygen to react with the fuel rich combustion product flow and form an exhaust flow from the combustion chamber; the first lance assembly (20, 28) is subsequently operable in the oxygen mode and the first regenerator is operable in the exhaust mode, and the second lance assembly (22, 30) is operable in the fuel gas mode and the second regenerator is operable in the firing mode to reverse the combustion flow and the exhaust flow within the combustion chamber to cycle between the first and second regenerators. a housing; a combustion chamber disposed within the housing; a charging end associated with the combustion chamber; a first port and a second port at the housing for communication with the combustion chamber at the charging end; a discharging end associated with the combustion chamber and spaced apart from the charging end; a first regenerator disposed at the charging end and in communication with the combustion chamber through the first port, the first regenerator adapted for cyclical operation between a firing mode wherein fuel is injected proximate preheated combustion air passing through the first port into the combustion chamber, and an exhaust mode wherein products of combustion are exhausted from the combustion chamber through the first port; a first lance assembly (20, 28) disposed only in the half of the combustion chamber closest to the discharging end and adapted for cyclical operation between a fuel gas mode in which it injects only fuel gas and an oxygen mode in which it injects only oxygen concurrent with the cyclical operation of the first regenerator; a second regenerator disposed at the charging end and in communication with the combustion chamber through the second port, the second regenerator adapted for cyclical operation between the firing mode wherein fuel is injected proximate preheated combustion air passing through the second port into the combustion chamber, and the exhaust mode wherein products of combustion are exhausted from the combustion chamber through the second port; and a second lance assembly (22, 30) disposed only in the half of the combustion chamber closest to the discharging end and adapted for cyclical operation between a fuel gas mode in which it injects only fuel gas and an oxygen mode in which it injects only oxygen concurrent with the cyclical operation of the second regenerator; wherein the first lance assembly (20, 28) is operable in a fuel gas mode concurrently with the firing mode of the first regenerator to provide fuel rich combustion and a fuel rich combustion product flow within the combustion chamber, and the second lance assembly (22, 30) is operable in an oxygen mode concurrently with the exhaust mode of the second regenerator to provide additional oxygen to react with the fuel rich combustion product flow and form an exhaust flow from the combustion chamber; the first lance assembly (20, 28) is subsequently operable in the oxygen mode and the first regenerator is operable in the exhaust mode, and the second lance assembly (22, 30) is operable in the fuel gas mode and the second regenerator is operable in the firing mode to reverse the combustion flow and the exhaust flow within the combustion chamber to cycle between the first and second regenerators.