adverb
in any case; anyway; after all
Used to emphasize a reason or situation that makes something inevitable or understandable. Often introduces a statement that explains or justifies what follows.
See also: 何せ
何しろ初めての海外旅行だから、緊張している。
After all, it's my first trip abroad, so I'm nervous.
Anyway, the opponent is a pro, so winning will be tough.
adverb
Functions like a conjunction giving a reason, often at the start of a sentence. Similar to なぜなら, but more colloquial and emphatic.
何しろ彼はまだ子供だから、許してあげよう。
Since he's still a child, let's forgive him.
何しろ時間がないので、手短に話します。
Because we don't have much time, I'll keep it brief.