Why France could not answer Plan Z alone

How large a French fleet would be needed to counter a 198-ship German Plan Z force?

France would want a force comparable to Germany and Italy combined but could not obtain it, so the Royal Navy would have to provide most of the balance.

A 198-ship German program cannot be answered by counting French ships against Germany alone because Italy also shapes the Mediterranean balance. French planners would ideally want numbers equivalent to the German and Italian fleets combined. That force was not obtainable. France would therefore have to rely on Britain to provide most of the naval counterweight, making alliance force allocation more important than nominal one-for-one parity.