Modern history does not indicate that we are becoming any less warlike. Technology and human behaviour have combined to make the twentieth century the bloodiest century on record. In World War I at the Christmases of 1916 and 1917, there are records of enemy soldiers exchanging gifts and friendship. During warfare, humans have carried out terrible atrocities against each other. Soldiers develop deep bonds of comradeship and loyalty for each other and to their regiment.
Nations spend a great deal of money and effort in preparing for war.