What has Mary Seacole got to do with it? She aided soldiers in the Crimean War (1853-1856). and nobody executed her for doing so. Edith Cavell was in WW1 and died for her principles
Nurses and doctors throughout time have a commendable record of treating soldiers from both sides equally. Vera Brittain describes nursing German soldiers in British Army hospitals in France at this time. Others, like Edith Cavell, helped nurse resistance workers as well.
She was unfortunate to be caught, sent to trial, condemned and executed. The government made a big deal over her trial and death because at that time in WW1, there was a propaganda campaign on to show that the Germans were evil and bestial, killing babies, committing wholesale rape and other atrocities.
Her execution, a woman, and a noble nurse, who treated everyone, and died for her principles, gave the British and French government a superb propaganda coup.
Things are never quite what they seem to be. Would there have been all the publicity and the statue, if it hadn't been politically advantagious?