title:Forced withdrawal from an OP Stack blockchain
lang:en-US
---
## What is this?
Any assets you own on an OP Stack blockchain are backed by equivalent assets on the underlying L1, locked in a bridge.
In this article you learn how to withdraw these assets directly from L1.
Note that the steps here do require access to an L2 endpoint.
However, that L2 endpoint can be a read-only replica.
## Setup
The code to go along with this article is available at [our tutorials repository](https://github.com/ethereum-optimism/optimism-tutorial/tree/main/op-stack/forced-withdrawal).
1. Clone the repository, move to the correct directory, and install the required dependencies.
| L1URL | URL to L1 (Goerli if you followed the directions on this site)
| L2URL | URL to the L2 from which you are withdrawing
| PRIV_KEY | Private key for an account that has ETH on L2. It also needs ETH on L1 to submit transactions
| OPTIMISM_PORTAL_ADDR | Address of the `OptimismPortalProxy` on L1.
## Withdrawal
### ETH withdrawals
The easiest way to withdraw ETH is to send it to the bridge, or the cross domain messenger, on L2.
1. Enter the Hardhat console.
```sh
npx hardhat console --network l1
```
1. Specify the amount of ETH you want to transfer.
This code transfers one hundred'th of an ETH.
```js
transferAmt=BigInt(0.01*1e18)
```
1. Create a contract object for the [`OptimismPortal`](https://github.com/ethereum-optimism/optimism/blob/develop/packages/contracts-bedrock/contracts/L1/OptimismPortal.sol) contract.
1. To [prove](https://sdk.optimism.io/classes/crosschainmessenger#proveMessage-2) and [finalize](https://sdk.optimism.io/classes/crosschainmessenger#finalizeMessage-2) the message we need the hash.
Optimism's [core-utils package](https://www.npmjs.com/package/@eth-optimism/core-utils) has the necessary function.
This step, and subsequent ETH withdrawal steps, are explained in [this tutorial](https://github.com/ethereum-optimism/optimism-tutorial/tree/main/cross-dom-bridge-eth).
Your L1 balance doesn't increase by the entire `transferAmt` because of the cost of `crossChainMessenger.finalizeMessage`, which submits a transaction.