As we read SM Stirling's Conquistador (New York, 2004), we find that the date of the action matters. The novel is copyright 2003 but set in 2009, the future. There has been a recent war:
"'...they tightened up on security a lot during the war, with identity cards and biometric scanners all over the place.'" (p. 39)
Our hero, Tom Christiansen saw action and took a bullet wound during that war but we have not been told any details of the conflict as far as I have read.
Secondly, there are three pieces of future technology:
a Segway is a small two-wheel computerized electric scooter with its rider standing on a platform, lawsuits and regulations keeping them out of towns;
a hooded scanner above a hospital bed monitors brain activity and a variant electronic process hastens healing by generating an analogue of natural sleep;
display glasses with small microphones attached play recorded wraparound 3D moving images distinguishable from reality only by the fact that the person wearing the glasses cannot change his viewpoint by turning his head.
We might be puzzled to read about this technology in 2009 until we check the date of publication. As a rule, alternative timeline stories start from the author's "present," not from his near future, but a writer of Stirling's inventiveness is not bound by any rules.