As it chanced, some alternative terms that can be used to convey the same meaning include "by chance," "unexpectedly," "fortuitously," "by coincidence," "accidentally," and "unplanned." These synonyms can be used as a replacement for "as it chanced" in a sentence to indicate that something occurred in an unforeseen or unusual manner, without prior planning or anticipation. Whether you are recounting a story or writing a narrative, these synonyms can be useful in lending variety and depth to your writing and making it more interesting.