Conversation so far:
What are the brisbane bears in relation to Robert Walls?
Robert Walls coached the Brisbane Bears from 1991–1995.
Are there any other interesting aspects about this Robert Walls article aside from Walls who coached the Brisbane Bears from 1991–1995?
the Brisbane Bears players donned boxing gloves and beat 21-year-old teammate Shane Strempel repetitively in the head
What was the cause of the players beating 21-year-old teammate Shane Strempel repetitively in the head?
as disciplinary action Robert Walls authorised his players to beat Shane Strempel
Why was Shane Strempel disciplined by Walls and his players?
Robert Walls had intended to teach the Swans Districts recruit Shane Strempel to respect his team-mates
How did Robert Walls' team the Brisbane Bears take to Shane Strempel being disciplined?
Shane Strempel was severely bashed and bloodied after which Strempel quit playing football.
Were any team mates arrested for the assault after which Strempel quit playing football being severely bashed and bloodied
What happened to Robert Walls after the brutal beating of Shane Strempel where he was severely bashed and bloodied?
Robert Walls's coaching style was criticised about the incident by Kevin Sheedy who has several times questioned his credibility as a football coach.

Question: When did he reitre?
Self-contained rewrite: When did Robert Walls retire from coaching?