Short answers, pulled from the story.
Land warfare, also called ground warfare, is the process of military operations resulting in combat that takes place predominantly on the land surface of the planet. It is characterized by large numbers of combat personnel using diverse weapon systems, conducted across varied terrains and weather conditions.
Since World War II, land combat has largely involved three distinct types of combat units: infantry, armour, and artillery. Each arm brings different capabilities, and they are typically combined to achieve mutually complementary effects on the battlefield.
The word artillery is derived from the Old French verb attilier, meaning "to equip". Historically it referred to any engine used to discharge projectiles during war, as well as the ground troops who manned those weapons.
Combined arms is an approach to warfare that integrates different military branches, such as self-propelled artillery, mechanized infantry, and aircraft, to achieve mutually complementary effects. The goal is for each element to compensate for the weaknesses of the others.
Land warfare is conducted in and around urban and rural population areas where people actually live. Because it directly involves the defence of civilian territory, it is the primary focus for most national defence policy planning and financial considerations.
Land warfare is conducted across diverse terrains and weather environments, including arctic, desert, jungle, mountain, and urban settings. Each environment imposes distinct physical and tactical constraints on the forces operating within it.