Machine guns inflicted appalling casualties on both war fronts in World War One. Men who went over-the-top in trenches stood little chance when the enemy opened up with their machine guns. Machine guns were one of the main killers in the war and accounted for many thousands of deaths
When God said this, he meant that he will show his love to (whoever) and not take it away like he did to Saul before. Saul did things (sin) to make God stop showing his love or compassion to him.