I looked in the strat FAQ and it says you have to reinforce BEFORE 19 hours before a battle is scheduled. But I swore it was different for attackers and defenders. I thought it used to be that attackers had to reinforce 23 hours before a battle (basically an hour after attacking) and that defenders had up til 5 hours before a battle to reinforce...apparently you have 5 hours after being attacked to reinforce...
19 hours before the battle is scheduled, yes, so unless the battle log is backed up or the battle is postponed by night time (I'm not 100% sure night time counts), that comes to 5 hours after the attack is initially launched, because the default wait time for any battle is 24 hours. 24-19=5. This was previously true for both sides, now it only holds for defenders. Attackers only have 2 hours to reinforce after launching the attack, and IIRC this isn't affected by postponements.
It was never the case for either side that you had until 5 hours before the battle (19 hours after launching) to reinforce.
You have 5 hours from the initial confrontation I do believe.
So If you get attacked at 12 you have until 7 to reinforce and after that you are on your own.
12+5=19
??!?!?!