looks, sexual prowess, etc., or mixes of such traits, practices that led to a horrific "Final War" on Old Earth. Long-established and advanced daughter colonies like Beowulf mounted a variety of rescue missions and initiated a thousand-year effort to clean up the Earth gene pool. For a time, the cultural centre moved off the Earth as it took about 500 years for the planetary economy to recover its pre-eminence within its shell of highly populated, highly developed planets. Located in the center of the spherical Solarian League, Earth's Old Chicago eventually re-emerged as the nominal League Capital. By the Gregorian calendar currently in use, the Honorverse novels are dated beginning with year 2103 A.D.—the epoch date of the Diaspora's beginning. The FTL hyperspace propulsion system in the stories is around 600 years old at the time period in which the novels are placed. This technology uses the ability to "sail" along a vast network of "gravity waves" on different successively higher hyperbands, each higher band giving a more-efficient speed multiplier but requiring more powerful (therefore bulkier and more expensive) engines to reach; the higher bands significantly shortening transit times on a given gravity wave for a given base speed, which is limited by particle densities and radiation shielding as Newtonian speeds increase. Analogous to prevailing trade winds creating certain favoured sea routes on Earth, the relatively static fixed gravity waves form favoured travel paths. A lack of gravity waves in some regions means that they must be plodded across by relatively slower means. These favorite routes and desert crossing points are susceptible to illegitimate exploitation by pirates and commerce-raiding warships, both interested in preying on the rich pickings of the interstellar merchant cargo ships that carry upwards of 2–7 million metric tonnes of cargo. Within each hyperband, ships have a local speed limited by particle densities that, at high relative speeds, become cosmic radiation. Better physical shielding or a better particle shield generator enables faster speeds within the band, on which base speed, multiplied by that band's multiplier, results in shorter journey times. Merchant ships have immense size and thin walls with virtually no physical shielding, as well as cheaper, relatively weak particle shield generators and hyper generators. Commercial carriers, like sailing ships and freight trains of Old Earth, trade off journey time by increased size and volume carried, so as to keep shipping costs economical. Military vessels, having no