\vspace doesn't work

Question

This is a very simple document. Yet, \vspace doesn't work:

\begin{titlepage}
Dies ist ein Test.
\vspace{5cm}
Dies ist ein Test.
\end{titlepage}

Whats wrong here?

Answer 1

Quoting from Leslie Lamport’s LaTeX: A Document Preparation System, p. 216,:

\vspace {len}
\vspace*{len}

Add a vertical space of length len. If the command appears in the middle of a paragraph, then the space is added after the line containing it.

This is what happens in your case.

Edit: The quotation continues:

The space produced by \vspace is removed if it falls at a page break; that produced by \vspace* is not.

Now, this is exactly the case if you remove the first line “Dies ist ein Test.”: indeed, the titlepage environment forces a page break at its beginning. So, if you want the space not to disappear there, you must use \vspace*.