When neutrons scatter off protons the energy often ends up shared, since the masses are about equal. Pretty soon the neutron becomes thermal, pottering about fo

When neutrons scatter off protons the energy often ends up shared, since the masses are about equal. Pretty soon the neutron becomes thermal, pottering about for a bit, until its half life of only 10 minutes leads to decay. So materials rich in protons, such as wet soil, provide useful shielding. When neutrons scatter off iron they bounce. It is a random walk, but they keep up their speed. Tank armour is mostly iron. It isn't much good against neutrons, even though it is great against the blast and heat of ordinary nuclear weapons. The obvious tactic is to have your infantry cower in muddy trenches while your neutron bombs inflict disproportionate casualties on invading enemy tanks. That is where neutron bombs fitted into the cold war.