The title ‘The Soldier’ suggests an anonymous person, reflecting how many soldiers died during WWI. It is a sonnet, a love poem to England.
Opening line “If I should die” suggests an acceptance of death and modal verb “should” indicates a willingness to die for his country.
The words “richer dust” suggests the remains of his body are superior to the ground he lies in because he is English, not foreign. Dust also relates to the religious idea of our bodies becoming “dust” when we die.
“A pulse in the eternal mind” suggests his presence in the soil of foreign land will always live on, making him immortal.
“under an English heaven” shows his pride in England as he is suggesting England is almost like paradise and to die in England’s name would bring him “peace”.