A combustion section for a gas turbine engine, the combustion section defining a radial direction, a circumferential direction, a longitudinal centerline extended along a longitudinal direction, and a forward direction toward a downstream end and an aft direction toward an upstream end, the combustion section comprising: a combustor assembly comprising: an inner liner and an outer liner each extended at least partially along a lengthwise direction and at an acute angle relative to the longitudinal centerline; a dome assembly extended between the inner liner and the outer liner, wherein the dome assembly, the inner liner, and the outer liner together define a combustion chamber therebetween; and a bulkhead assembly defining a plurality of walls coupled to the inner liner and generally surrounding the outer liner and dome assembly, wherein at least a portion of the bulkhead assembly is extended at least partially along a forward direction and defines a plenum between the bulkhead assembly and the dome assembly; an outer casing surrounding the combustor assembly, wherein the outer casing is extended at least partially co-directional to the combustor assembly; a fuel injector assembly extended through the outer casing, the bulkhead assembly, and the dome assembly; and an inner casing, wherein the outer casing, the inner casing, and the combustor assembly together define a primary flowpath in direct fluid communication with the combustion chamber, and wherein the primary flowpath is extended at least along a forward direction and an aft direction defined by inner casing, the outer casing, and the combustor assembly, and wherein an oxidizer flows through the primary flowpath in serial flow through the plenum and the fuel injector assembly into the combustion chamber. an inner liner and an outer liner each extended at least partially along a lengthwise direction and at an acute angle relative to the longitudinal centerline; a dome assembly extended between the inner liner and the outer liner, wherein the dome assembly, the inner liner, and the outer liner together define a combustion chamber therebetween; and a bulkhead assembly defining a plurality of walls coupled to the inner liner and generally surrounding the outer liner and dome assembly, wherein at least a portion of the bulkhead assembly is extended at least partially along a forward direction and defines a plenum between the bulkhead assembly and the dome assembly; an outer casing surrounding the combustor assembly, wherein the outer casing is extended at least partially co-directional to the combustor assembly; a fuel injector assembly extended through the outer casing, the bulkhead assembly, and the dome assembly; and an inner casing, wherein the outer casing, the inner casing, and the combustor assembly together define a primary flowpath in direct fluid communication with the combustion chamber, and wherein the primary flowpath is extended at least along a forward direction and an aft direction defined by inner casing, the outer casing, and the combustor assembly, and wherein an oxidizer flows through the primary flowpath in serial flow through the plenum and the fuel injector assembly into the combustion chamber.