XSLT template does not apply to all elements

I am confused about the use of XSLT templates and when/how they are applied. Suppose I have the following XML file:

<book>
  <chapter> 1 </chapter>
  <chapter> 2 </chapter>
</book>

and I'd like to match all chapters in order. This is a XSLT stylesheet:

<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://ift.tt/tCZ8VR" >
  <xsl:template match="book">                                                     
    <h1>book</h1>                                                               
  </xsl:template>                                                                 
  <xsl:template match="chapter">                                                  
    <h2>chapter <xsl:value-of select="."/></h2>                                   
  </xsl:template>                                                                                                                                                 
</xsl:stylesheet>                                                               

The result of the stylesheet is

<h1>book</h1>

without the expected numeration of chapters. Adding an <xsl:apply-templates /> at the end of the book matching template didn't help. I'd like to do without an xls:for-each though.