Do I have to include employment dates?

Absolutely.
Long durations of unemployment between jobs are one of the first red flags that recruiters look for when reviewing a CV. Recruiters will immediately suspect you of trying to disguise employment gaps if you don’t include dates of work. Include an explanation on your resume or in your cover letter if you’re concerned about a short duration at a job owing to a layoff. Similarly, rather of trying to hide a resume gap caused by reasons beyond your control, such as a health or family crisis, show your integrity and honesty by stating it clearly on your resume.