user: Question: What is the minimum laid down?
Columns: ['Ship', 'Builder', 'Namesake', 'Renamed', 'Laid down', 'Launched', 'Commissioned or completed(*)']
Types: ['text', 'text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Ajax', 'Snowden & Mason, Pittsburgh, Pennsylvania', 'Manayunk, Philadelphia', 'Manayunk, 1862; Ajax, 15 June 1869', 1862.0, '18 December 1864', '27 September 1865*']
SQL:

assistant: SELECT MIN("Laid down") FROM "Table";